CN111058794B - Control method and device for applying back pressure to annulus - Google Patents
Control method and device for applying back pressure to annulus Download PDFInfo
- Publication number
- CN111058794B CN111058794B CN201911176664.2A CN201911176664A CN111058794B CN 111058794 B CN111058794 B CN 111058794B CN 201911176664 A CN201911176664 A CN 201911176664A CN 111058794 B CN111058794 B CN 111058794B
- Authority
- CN
- China
- Prior art keywords
- back pressure
- density
- time
- annulus
- target
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000000034 method Methods 0.000 title claims abstract description 38
- 239000004568 cement Substances 0.000 claims abstract description 256
- 239000002002 slurry Substances 0.000 claims abstract description 134
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 68
- 230000008859 change Effects 0.000 claims abstract description 19
- 238000004364 calculation method Methods 0.000 claims description 37
- 230000015271 coagulation Effects 0.000 claims description 2
- 238000005345 coagulation Methods 0.000 claims description 2
- 230000006870 function Effects 0.000 description 30
- 230000002706 hydrostatic effect Effects 0.000 description 12
- 230000005465 channeling Effects 0.000 description 9
- 230000004580 weight loss Effects 0.000 description 8
- 238000005553 drilling Methods 0.000 description 6
- 230000007423 decrease Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 230000036962 time dependent Effects 0.000 description 3
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000011440 grout Substances 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/10—Sealing or packing boreholes or wells in the borehole
- E21B33/13—Methods or devices for cementing, for plugging holes, crevices or the like
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
- E21B21/08—Controlling or monitoring pressure or flow of drilling fluid, e.g. automatic filling of boreholes, automatic control of bottom pressure
Landscapes
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Mechanical Engineering (AREA)
- Lining And Supports For Tunnels (AREA)
- Preparation Of Clay, And Manufacture Of Mixtures Containing Clay Or Cement (AREA)
Abstract
The invention discloses a control method and a control device for applying back pressure to an annulus, and belongs to the technical field of well cementation. The method comprises the following steps: after a casing is put into an oil and gas well and cement slurry is injected into an annular space between the oil and gas well and the casing, determining the real-time density of the cement slurry based on a change function of the density of the cement slurry along with time; determining a back pressure to be applied based on the real-time density of the cement slurry and the formation pressure equivalent density at the target location; this back pressure is applied to the annulus. The back pressure is gradually increased along with the increase of time, in the early stage of the waiting period of cement paste, the back pressure applied to the annular space is small, the problem that the pressure in the annular space is greater than the fracture pressure of the stratum is avoided, and therefore the probability of the well leakage phenomenon in the oil and gas well is reduced.
Description
Technical Field
The invention relates to the technical field of well cementation, in particular to a method and a device for controlling back pressure applied to an annulus.
Background
Cementing is the process of setting casing inside oil and gas well, injecting cement slurry into the space between the oil and gas well and the casing, and sealing the oil layer, the gas layer and the water layer inside the oil and gas well after the cement is coagulated. The casing in the oil and gas well can be protected through well cementation of the oil and gas well, the exploitation life of the oil and gas well can be prolonged, and the method is one of important links of oil and gas well drilling engineering.
During the period that the cement paste is converted from liquid to solid (namely the waiting period of the cement paste), the weight loss phenomenon of the cement paste occurs, so that the hydrostatic column pressure applied to the stratum by the cement paste is reduced, the hydrostatic column pressure applied to the stratum by the cement paste may not be capable of balancing the pressure of the stratum, and air channeling may be induced. Gas blow-by refers to the phenomenon in which gas in the formation enters the annulus and moves along the annulus towards the wellhead of the well. That is, during the waiting period of the cement paste, the weight loss phenomenon of the cement paste induces gas channeling. The gas channeling can cause the follow-up drilling engineering and exploitation engineering to be impossible and can also cause the scrapping effect of the whole well. At present, in order to avoid the generation of gas channeling, a pressure control device positioned at the wellhead position of an oil-gas well can be adopted to apply back pressure to an annular space during the waiting setting period of cement slurry, and the hydrostatic column pressure lost by the cement slurry is compensated through the back pressure so as to balance the formation pressure.
However, the back pressure applied to the annulus by the current pressure control equipment is a constant value, so that the back pressure may be too large in the early stage of the waiting setting period of cement paste, and further the pressure in the annulus is greater than the fracture pressure of the stratum, so that the well leakage phenomenon occurs in an oil and gas well.
Disclosure of Invention
The embodiment of the invention provides a method and a device for controlling back pressure applied to an annulus. The problem of the backpressure that prior art's earlier stage accuse pressure equipment was applyed to the annular space during waiting to congeal at the grout is too big, leads to the pressure in the annular space to be greater than the rupture pressure in stratum to lead to the phenomenon that takes place the lost circulation in the oil gas well is solved, technical scheme is as follows:
in one aspect, a control method for applying back pressure to an annulus is provided, and is applied to pressure control equipment which is positioned at a wellhead of an oil and gas well when the oil and gas well is well-cemented, and the method comprises the following steps:
after running a casing in the oil and gas well and injecting cement slurry into an annulus between the oil and gas well and the casing, determining the real-time density of the cement slurry based on a function of the density of the cement slurry over time;
determining back pressure to be applied based on the real-time density of the cement paste and the formation pressure equivalent density at a target position, so that the real-time density of the cement paste is in inverse proportion to the back pressure within a target time length, the target position is a position of a formation which is easy to leak in the oil-gas well, and the target time length is a time length when the gel strength of the cement paste reaches a specified value;
applying the back pressure to the annulus;
wherein the variation function of the density of the cement paste along with time is as follows:
and the ESD is the density of the cement paste, and t is the time length after the cement paste is injected into the annulus.
Optionally, determining the back pressure to be applied based on the real-time density of the cement slurry and the formation pressure equivalent density at the target location comprises:
detecting whether the time length of the cement slurry after being injected into the annulus is less than a target time length;
when the time length of the cement paste after being injected into the annulus is less than the target time length, calculating the back pressure to be applied by adopting a first back pressure calculation formula on the basis of the density of the cement paste at the current time and the formation pressure equivalent density at the target position; the first back pressure calculation formula is as follows:
wherein, P0For the back pressure to be applied, GpIs the formation pressure equivalent density at the target location,△Gpis a safe value of formation pressure equivalent density at the target location, H is a vertical height of cement slurry above the target location, t0Is the target duration.
Optionally, after detecting whether the time period elapsed after the cement slurry is injected into the annulus is less than a target time period, the method further includes:
when the time length of the cement paste after being injected into the annulus is not less than the target time length, calculating the back pressure to be applied by adopting a second back pressure calculation formula on the basis of the density of the cement paste at the target time length and the formation pressure equivalent density at the target position; the second back pressure calculation formula is as follows:
optionally, the target time period is a time period when the cement slurry has a gel strength of 240 pa.
Optionally, after applying the back pressure to the annulus, the method further includes:
and after a specified time, stopping applying the back pressure to the annulus, wherein the specified time is the setting time of the cement paste.
On the other hand, provide a controlling means who exerts back pressure to the annular space, be applied to when cementing the oil and gas well, be located the accuse pressure equipment of well head department of oil and gas well, the device includes:
a first determination module for determining a real-time density of a cement slurry based on a function of a change in density of the cement slurry over time after running a casing in the well and injecting the cement slurry into an annulus between the well and the casing;
the second determination module is used for determining back pressure to be applied based on the real-time density of the cement paste and the formation pressure equivalent density at a target position, so that the real-time density of the cement paste is in inverse proportion to the back pressure in a target time length, the target position is the position of a formation which is easy to leak in the oil-gas well, and the target time length is the time length when the gel strength of the cement paste reaches a specified value;
an application module for applying the back pressure to the annulus;
wherein the variation function of the density of the cement paste along with time is as follows:
and the ESD is the density of the cement paste, and t is the time length after the cement paste is injected into the annulus.
Optionally, the second determining module is configured to:
detecting whether the time length of the cement slurry after being injected into the annulus is less than a target time length;
when the time length of the cement paste after being injected into the annulus is less than the target time length, calculating the back pressure to be applied by adopting a first back pressure calculation formula on the basis of the density of the cement paste at the current time and the formation pressure equivalent density at the target position; the first back pressure calculation formula is as follows:
wherein, P0For the back pressure to be applied, GpIs the formation pressure equivalent density, Δ G, at the target locationpIs a safe value of formation pressure equivalent density at the target location, H is a vertical height of cement slurry above the target location, t0Is the target duration.
Optionally, the second determining module is configured to:
when the time length of the cement paste after being injected into the annulus is not less than the target time length, calculating the back pressure to be applied by adopting a second back pressure calculation formula on the basis of the density of the cement paste at the target time length and the formation pressure equivalent density at the target position; the second back pressure calculation formula is as follows:
optionally, the target time period is a time period when the cement slurry has a gel strength of 240 pa.
Optionally, the apparatus further comprises:
and the application stopping module is used for stopping applying the back pressure to the annular space after a specified time, wherein the specified time is the coagulation time of the cement paste.
The technical scheme provided by the embodiment of the invention has the beneficial effects that the technical scheme at least comprises the following steps:
determining the real-time density of the cement slurry through a function of the density of the cement slurry along with time, and determining the back pressure to be applied based on the real-time density of the cement slurry and the formation pressure equivalent density at the target position. When the pressure control equipment applies the back pressure to the annulus, the hydrostatic column pressure lost by cement slurry can be effectively compensated so as to balance the formation pressure. Since the real-time density of the cement slurry is inversely proportional to the back pressure, and the real-time density of the cement slurry gradually decreases with the increase of time after the cement slurry is injected into the annulus, the finally determined back pressure to be applied is also different, and the back pressure gradually increases with the increase of time. In the early stage of the waiting period of cement paste, the back pressure applied to the annulus is small, so that the problem that the pressure in the annulus is greater than the fracture pressure of the stratum is avoided, and the probability of the well leakage phenomenon in the oil-gas well is reduced.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic diagram of an implementation environment of a control method for applying back pressure to an annulus according to an embodiment of the present invention;
FIG. 2 is a flow chart of a method of controlling the application of back pressure to an annulus according to an embodiment of the present invention;
FIG. 3 is a flow chart of another method of controlling the application of back pressure to an annulus provided by an embodiment of the present invention;
FIG. 4 is a graph of cement slurry density versus cement slurry set time provided by an embodiment of the present invention;
FIG. 5 is a block diagram of a control device for applying back pressure to an annulus according to an embodiment of the present invention;
fig. 6 is a block diagram of another control device for applying back pressure to an annulus according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Referring to fig. 1, fig. 1 is a schematic view of an implementation environment of a control method for applying back pressure to an annulus according to an embodiment of the present invention. The implementation environment includes: a hydrocarbon well 101 and a pressure control device 102 located at the wellhead of the hydrocarbon well 101. When it is desired to cement the well 101, a casing 103 may be lowered into the well 101 and a cement slurry 105 injected into the annulus 104 between the well 101 and the casing 102. During the waiting period of the cement paste 105, the cement paste 105 can generate a weight loss phenomenon to induce gas channeling. To reduce the probability of gas breakthrough, back pressure may be applied to the annulus 104 by the pressure control device 102.
Referring to fig. 2, fig. 2 is a flowchart of a control method for applying back pressure to an annulus according to an embodiment of the present invention. The control method for applying the back pressure to the annulus is applied to the pressure control device 102 in the implementation environment shown in fig. 1. The control method for applying the back pressure to the annular space can comprise the following steps:
Wherein the change function of the density of the cement paste along with time is as follows:
wherein ESD is the density of cement paste, and t is the time length after the cement paste is injected into the annulus.
The target time duration is the time duration for which the cement slurry gel strength reaches the specified data. The target position is a position of a formation which is easy to leak in the oil-gas well. The formation with the lowest pressure loss in the well is referred to as the formation with the lowest pressure loss.
In the embodiment of the invention, during the waiting period of the cement paste, the weight loss phenomenon of the cement paste occurs, namely, the density of the cement paste is gradually reduced along with the increase of time, so that the hydrostatic column pressure applied by the cement paste to a target position is reduced. Therefore, the pressure control equipment in the embodiment of the invention can determine the real-time density of the cement slurry based on the change function of the density of the cement slurry along with time, and then determine the back pressure to be applied based on the real-time density of the cement slurry and the formation pressure equivalent density at the target position.
In the embodiment of the present invention, after the pressure control device determines the back pressure to be applied through the step 202 based on the real-time density of the cement slurry and the formation pressure equivalent density at the target position, the pressure control device may apply the back pressure to the annulus, and may effectively compensate the hydrostatic column pressure lost by the cement slurry to balance the formation pressure.
In summary, the control method for applying back pressure to an annulus provided in the embodiments of the present invention determines the real-time density of the cement slurry through the change function of the density of the cement slurry with time, and determines the back pressure to be applied based on the real-time density of the cement slurry and the formation pressure equivalent density at the target location. When the pressure control equipment applies the back pressure to the annulus, the hydrostatic column pressure lost by cement slurry can be effectively compensated so as to balance the formation pressure. Since the real-time density of the cement slurry is inversely proportional to the back pressure, and the real-time density of the cement slurry gradually decreases with the increase of time after the cement slurry is injected into the annulus, the finally determined back pressure to be applied is also different, and the back pressure gradually increases with the increase of time. In the early stage of the waiting period of cement paste, the back pressure applied to the annulus is small, so that the problem that the pressure in the annulus is greater than the fracture pressure of the stratum is avoided, and the probability of the well leakage phenomenon in the oil-gas well is reduced.
Referring to fig. 3, fig. 3 is a flowchart of another control method for applying back pressure to an annulus according to an embodiment of the present invention. The control method for applying the back pressure to the annulus is applied to the pressure control device 102 in the implementation environment shown in fig. 1. The control method for applying the back pressure to the annular space can comprise the following steps:
In embodiments of the invention, after running casing in an oil and gas well and injecting cement slurry into the annulus between the oil and gas well and the casing, the pressure control device may determine the real-time density of the cement slurry based on a function of the density of the cement slurry over time. The density of the cement slurry as a function of time may be:
wherein ESD is the density of cement paste, and t is the time length after the cement paste is injected into the annulus.
It should be noted that, before the pressure control device determines the real-time density of the cement slurry based on the time-varying function of the density of the cement slurry, the pressure control device needs to acquire the time-varying function of the density of the cement slurry.
In the embodiment of the invention, the change function of the density of the cement along with the time can be obtained through experimental equipment. For example, the experimental facility may obtain the density of the cement as a function of time through several procedures as follows.
Firstly, the experimental equipment can obtain the corresponding relation between the density of the cement paste and the waiting setting time of the cement paste through a simulation experiment. The waiting time of the cement paste is the time length after the cement paste is injected into the annulus in the embodiment of the present invention. The corresponding relationship between the density of the cement paste and the setting time of the cement paste can be referred to table 1.
TABLE 1
As is apparent from Table 1, when the waiting time of the cement paste is 0 (i.e., when the cement paste has just started to set), the density of the cement paste is 1.91g/cm3(ii) a When the waiting setting time of the cement paste is 10min, the density of the cement paste is 1.88g/cm3。
Then, the experimental facility can simulate the change curve of the density of the cement paste with time as shown in fig. 4 according to the corresponding relationship between the density of the cement paste and the waiting time of the cement paste shown in table 1. The curve follows the following curve function:
finally, the experimental facility can fit out the following parameters based on the curve function and the corresponding relationship between the density of the cement paste and the waiting setting time of the cement paste: a is 0.976, b is 0.927, c is 34.617, and k is 3.36, and the variation function of the density of the cement paste along with time can be obtained:
it should be noted that, after the experimental device obtains the change function of the density of the cement slurry with time, in a possible implementation manner, the experimental device may send the change function of the density of the cement slurry with time to the pressure control device, and at this time, the pressure control device may obtain the change function of the density of the cement slurry with time sent by the experimental device.
In another possible implementation manner, a worker may input the time-dependent change function of the density of the cement slurry, which is obtained by the experimental equipment, into the pressure control equipment based on the time-dependent change function of the density of the cement slurry, so that the pressure control equipment can obtain the time-dependent change function of the density of the cement slurry.
The target duration can be the duration when the cement paste is injected into an annulus between an oil-gas well and a casing and the gel strength of the cement paste reaches a specified value. Alternatively, the target time period is a time period when the cement paste has reached a gel strength of 240 Pa. The target time period can be obtained by experiment.
In the embodiment of the invention, when the gel strength of the cement paste in the annulus is less than 240 Pa, the probability of inducing gas channeling due to the weight loss phenomenon of the cement paste is high, and the magnitude of the back pressure applied to the annulus by the pressure control equipment needs to be continuously increased. When the gel strength of the cement paste in the annulus is greater than or equal to 240 Pa, the weight loss phenomenon of the cement paste can not induce gas channeling any more, the back pressure applied to the annulus by the pressure control equipment does not need to be increased continuously, and the back pressure applied to the annulus by the pressure control equipment is a fixed value at the moment.
Thus, the manner in which the pressure control apparatus calculates the back pressure to be applied differs when the cement slurry is at a gel strength of less than 240 pa, and when the cement slurry is at a gel strength of greater than or equal to 240 pa. In the embodiment of the present invention, the pressure control device needs to detect whether the time elapsed after injecting into the annulus is less than the target time, and when the pressure control device detects that the time elapsed after injecting cement slurry into the annulus is less than the target time, step 303 is executed; when the time length of the cement slurry injected into the annulus, which is detected by the pressure control equipment, is not less than the target time length, step 304 is executed.
And 303, when the time length of the cement paste injected into the annulus is less than the target time length, calculating the back pressure to be applied by adopting a first back pressure calculation formula based on the density of the cement paste at the current time and the formation pressure equivalent density at the target position.
In the embodiment of the invention, when the time length elapsed after the cement slurry is injected into the annulus is detected by the pressure control equipment to be less than the target time length, the pressure control equipment can calculate the back pressure to be applied by adopting a first back pressure calculation formula based on the density of the cement slurry at the current time and the formation pressure equivalent density at the target position.
Wherein, the first back pressure calculation formula is:
wherein, P0For back pressure to be applied, GpIs the formation pressure equivalent density, Δ G, at the target locationpIs a safe value for formation pressure equivalent density at the target location, H is the vertical height of the cement slurry above the target location, t0For the target duration, t is the elapsed duration after the cement slurry is injected into the annulus.
Based on the first back pressure calculation formula, when the time length of the cement paste passing through the annulus after being injected into the annulus is less than the target time length, the density of the cement paste is reduced along with the increase of the time length of the cement paste passing through the annulus after being injected into the annulus, and the back pressure to be applied is increased along with the increase of the time length of the cement paste passing through the annulus after being injected into the annulus. Thus, the real-time density of the cement slurry over the target time period is inversely proportional to the back pressure to be applied.
Note that the formation pressure equivalent density G at the target locationpAnd a safety value Δ G for formation pressure equivalent density at the target locationpMay be obtained from drilling data acquired while drilling the well to obtain the oil and gas well.
And 304, when the time length of the cement paste after being injected into the annulus is not less than the target time length, calculating the back pressure to be applied by adopting a second back pressure calculation formula based on the density of the cement paste in the target time length and the formation pressure equivalent density at the target position.
In the embodiment of the invention, when the time length passed after the pressure control equipment detects that the cement slurry is injected into the annulus is not less than the target time length, the pressure control equipment can calculate the back pressure to be applied by adopting a second back pressure calculation formula based on the density of the cement slurry in the target time length and the equivalent density of the formation pressure at the target position.
The second back pressure calculation formula may be:
wherein, P0For back pressure to be applied, GpIs the formation pressure equivalent density, Δ G, at the target locationpIs the safe value of the formation pressure equivalent density at the target location, H is the vertical height of the cement slurry above the target location, t0Is the target duration.
Based on the second back pressure calculation formula, when the time that the cement paste passes after being injected into the annulus exceeds the target time length, the gel strength of the cement paste reaches 240 Pa, and the weight loss phenomenon of the cement paste can not induce gas channeling any more, so that the back pressure to be applied is not required to be continuously increased subsequently, and the back pressure to be applied is ensured to be always: and calculating the back pressure to be applied after the cement slurry is injected into the annular space for the target time length. A
In the embodiment of the present invention, after the pressure control device calculates the back pressure to be applied based on the first back pressure calculation formula or the second back pressure calculation formula, the pressure control device may apply the back pressure to the annulus.
For example, when the time length elapsed after the cement slurry is injected into the annulus is within the target time length, the pressure control device needs to calculate the back pressure to be applied by using the first back pressure calculation formula. At this time, the real-time density of the cement slurry is inversely proportional to the back pressure to be applied, and therefore, the back pressure applied to the annulus by the pressure control device is gradually increased as the time period elapsed after the cement slurry is injected into the annulus increases. The pressure control equipment can effectively compensate the hydrostatic column pressure of cement slurry loss to balance the formation pressure, guarantee that the back pressure applied to the annular space is small in the early stage of the waiting period of cement slurry, avoid the problem that the pressure in the annular space is greater than the fracture pressure of the formation, and reduce the probability of the phenomenon of well leakage in an oil-gas well.
When the time length of the cement slurry after being injected into the annulus exceeds the target time length, the pressure control equipment needs to adopt a second back pressure calculation formula to calculate the back pressure to be applied, at the moment, the gel strength of the cement slurry reaches 240 Pa, and the weight loss phenomenon of the cement slurry can not induce gas channeling any more, so that the pressure control equipment can continuously apply the same back pressure to the annulus. The pressure control equipment can reduce the back pressure applied to the annulus on the premise of balancing the formation pressure, so that the energy consumption of the pressure control equipment is reduced. The back pressure of the pressure control device for the time of the annulus may be the back pressure to be applied calculated at the target time period elapsed after the cement slurry is injected into the annulus.
Optionally, before the pressure control device applies back pressure to the annulus, the pressure control device further needs to perform the following steps:
and A, detecting whether the actual pressure equivalent density at the target position is greater than the specified equivalent density.
The actual pressure equivalent density is determined based on the back pressure to be applied and a safe value of the formation pressure equivalent density at the target location and the formation pressure equivalent density at the target location. For example, the actual pressure equivalent density may be calculated by using an actual pressure equivalent density calculation formula, where the actual pressure equivalent density calculation formula is:
wherein G is1Is the actual pressure equivalent density, P, at the target location0Is the back pressure to be applied calculated based on step 303 or step 304.
The specified equivalent density is determined based on the burst pressure equivalent density at the target location and a burst pressure equivalent density safety value at the target location. For example, the specified equivalent density can be calculated by using a specified equivalent density calculation formula, where the specified equivalent density calculation formula is:
G2＝Gf－△Gf；
wherein G is2To specify the equivalent density, GfIs the burst pressure equivalent density, Δ G, at the target locationfIs a safe value for burst pressure equivalent density at the target location. The burst pressure equivalent density G at the target position isfAnd a safe value Δ G of formation pressure equivalent density of fracture pressure at the target locationfMay be obtained from drilling data acquired while drilling the well to obtain the oil and gas well.
In the embodiment of the present invention, the pressure control apparatus needs to detect whether the actual pressure equivalent density at the target position is greater than the specified equivalent density. When the actual pressure equivalent density at the target position is not greater than the specified equivalent density, step 305 is performed, that is, the pressure control device applies the back pressure to be applied, which is calculated in step 303 or step 304, to the annulus. Step B is performed when the applied pressure equivalent density at the target location is greater than the specified equivalent density.
And step B, when the actual pressure equivalent density at the target position is larger than the specified equivalent density, determining new back pressure based on the specified equivalent density.
For example, the pressure control device may determine a new back pressure based on the specified equivalent density when the pressure control device detects that the actual pressure equivalent density at the target position is greater than the specified equivalent density. For example, the pressure control apparatus may calculate the new back pressure using a new back pressure calculation formula:
P0’＝0.00981×H×(Gf－ΔGf-ESD); wherein，P0' is new back pressure.
And step C, determining the new back pressure as the back pressure to be applied to the annulus by the pressure control equipment.
In the embodiment of the present invention, after determining the new back pressure as the back pressure to be applied to the annulus by the pressure control device, the pressure control device performs step 305, that is, the pressure control device applies the new back pressure to the annulus.
And step 306, stopping applying the back pressure to the annulus after a specified time period.
In the embodiment of the invention, after a specified time period, the pressure control equipment can stop applying back pressure to the annulus. The specified time period may be a setting time period of the cement paste, that is, a time period in which the cement paste is changed from a liquid state to a solid state. It should be noted that the setting time of the cement slurry is obtained through experiments. For example, the specified time period may be 8 hours, and the pressure control device may stop applying the back pressure to the annulus after applying the back pressure to the annulus for 8 hours.
Assuming that the vertical height of the cement slurry above the target position is 1400m (meters), and the initial hydrostatic column pressure of the cement slurry at the target position after the cement slurry is injected into the annulus is 11.67MPa (megapascals), the relationship between the elapsed time after the cement slurry is injected into the annulus (also referred to as the cement slurry waiting time) and the back pressure applied to the annulus by the pressure control equipment is shown in table 2.
TABLE 2
When the waiting time is 5min, the back pressure applied to the annulus by the pressure control equipment is 5.908 MPa; when the waiting time is 60min, the gel strength of the cement paste reaches 240 Pa, and after the waiting time is 60min, the pressure control equipment can continuously apply 10.045MPa of back pressure to the annulus; when the waiting time reaches 8 hours, the cement paste is converted from liquid state to solid state, and at the moment, the pressure control equipment can stop applying pressure to the annular space.
It should be noted that, the sequence of the steps of controlling the back pressure applied to the annulus provided in the embodiment of the present invention may be appropriately adjusted, and the steps may be increased or decreased according to the circumstances, and any method that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application, and therefore, no further description is given.
In summary, the control method for applying back pressure to an annulus provided in the embodiments of the present invention determines the real-time density of the cement slurry through the change function of the density of the cement slurry with time, and determines the back pressure to be applied based on the real-time density of the cement slurry and the formation pressure equivalent density at the target location. When the pressure control equipment applies the back pressure to the annulus, the hydrostatic column pressure lost by cement slurry can be effectively compensated so as to balance the formation pressure. Since the real-time density of the cement slurry is inversely proportional to the back pressure, and the real-time density of the cement slurry gradually decreases with the increase of time after the cement slurry is injected into the annulus, the finally determined back pressure to be applied is also different, and the back pressure gradually increases with the increase of time. In the early stage of the waiting period of cement paste, the back pressure applied to the annulus is small, so that the problem that the pressure in the annulus is greater than the fracture pressure of the stratum is avoided, and the probability of the well leakage phenomenon in the oil-gas well is reduced.
The embodiment of the invention provides a control device for applying back pressure to an annulus, which is applied to a pressure control device 102 in the implementation environment shown in fig. 1. By way of example, the apparatus may be the pressure control device 102 in the implementation environment shown in fig. 1, or may be integrated into the pressure control device 102. As shown in fig. 5, the control device 400 for applying back pressure to the annulus may include:
a first determining module 401 for determining a real-time density of the cement slurry based on a function of a change in density of the cement slurry with time after running the casing in the oil and gas well and injecting the cement slurry into an annulus between the oil and gas well and the casing.
The second determining module 402 is configured to determine a back pressure to be applied based on the real-time density of the cement slurry and the formation pressure equivalent density at the target location, so that the real-time density of the cement slurry within the target time duration is inversely proportional to the back pressure, the target location is a location of a formation that is prone to be lost in the oil and gas well, and the target time duration is a time duration when the gel strength of the cement slurry reaches a specified value.
And an applying module 403 for applying back pressure to the annulus.
Wherein the change function of the density of the cement paste along with time is as follows:
wherein ESD is the density of cement paste, and t is the time length after the cement paste is injected into the annulus.
In summary, the control device for applying back pressure to an annulus according to the embodiments of the present invention determines the real-time density of the cement slurry according to the time-varying function of the density of the cement slurry, and determines the back pressure to be applied based on the real-time density of the cement slurry and the formation pressure equivalent density at the target location. When the pressure control equipment applies the back pressure to the annulus, the hydrostatic column pressure lost by cement slurry can be effectively compensated so as to balance the formation pressure. Since the real-time density of the cement slurry is inversely proportional to the back pressure, and the real-time density of the cement slurry gradually decreases with the increase of time after the cement slurry is injected into the annulus, the finally determined back pressure to be applied is also different, and the back pressure gradually increases with the increase of time. In the early stage of the waiting period of cement paste, the back pressure applied to the annulus is small, so that the problem that the pressure in the annulus is greater than the fracture pressure of the stratum is avoided, and the probability of the well leakage phenomenon in the oil-gas well is reduced.
Optionally, the second determining module 402 is configured to: detecting whether the time length of the cement paste after being injected into the annulus is less than the target time length or not; when the time length of the cement paste after being injected into the annulus is less than the target time length, calculating the back pressure to be applied by adopting a first back pressure calculation formula based on the density of the cement paste at the current time and the formation pressure equivalent density at the target position; the first back pressure calculation formula is as follows:
wherein, P0For back pressure to be applied, GpIs the formation pressure equivalent density, Δ G, at the target locationpIs the safe value of the formation pressure equivalent density at the target location, H is the vertical height of the cement slurry above the target location, t0Is the target duration.
Optionally, the second determining module 402 is further configured to: when the time length of the cement paste after being injected into the annulus is not less than the target time length, calculating the back pressure to be applied by adopting a second back pressure calculation formula based on the density of the cement paste in the target time length and the formation pressure equivalent density at the target position; the second back pressure calculation formula is as follows:
alternatively, the target time period is a time period when the cement paste has reached a gel strength of 240 Pa.
Optionally, as shown in fig. 6, the control device 400 for applying back pressure to the annulus may further include: and a stop applying module 404, configured to stop applying back pressure to the annulus after a specified time period elapses, where the specified time period is a setting time period of the cement slurry.
In summary, the control device for applying back pressure to an annulus according to the embodiments of the present invention determines the real-time density of the cement slurry according to the time-varying function of the density of the cement slurry, and determines the back pressure to be applied based on the real-time density of the cement slurry and the formation pressure equivalent density at the target location. When the pressure control equipment applies the back pressure to the annulus, the hydrostatic column pressure lost by cement slurry can be effectively compensated so as to balance the formation pressure. Since the real-time density of the cement slurry is inversely proportional to the back pressure, and the real-time density of the cement slurry gradually decreases with the increase of time after the cement slurry is injected into the annulus, the finally determined back pressure to be applied is also different, and the back pressure gradually increases with the increase of time. In the early stage of the waiting period of cement paste, the back pressure applied to the annulus is small, so that the problem that the pressure in the annulus is greater than the fracture pressure of the stratum is avoided, and the probability of the well leakage phenomenon in the oil-gas well is reduced.
It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described apparatuses and modules may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
The embodiment of the invention also provides a computer-readable storage medium, wherein at least one instruction is stored in the storage medium, and the instruction is loaded and executed by a processor to realize the control method for applying the back pressure to the annulus shown in fig. 2 or fig. 3.
An embodiment of the present invention further provides a pressure control apparatus, including: a processor and a memory, the memory having stored therein at least one instruction that is loaded and executed by the processor to implement the control method for applying back pressure to an annulus as illustrated in fig. 2 or 3.
In embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. The term "plurality" means two or more unless expressly limited otherwise.
It will be understood by those skilled in the art that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by a program instructing relevant hardware, where the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, etc.
The above description is only exemplary of the present invention and should not be taken as limiting, and any modifications, equivalents, improvements and the like that are within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. A method of controlling the back pressure applied to an annulus, for use with a pressure control device located at the wellhead of an oil or gas well when cementing the well, the method comprising:
after running a casing in the oil and gas well and injecting cement slurry into an annulus between the oil and gas well and the casing, determining the real-time density of the cement slurry based on a function of the density of the cement slurry over time;
determining back pressure to be applied based on the real-time density of the cement paste and the formation pressure equivalent density at a target position, so that the real-time density of the cement paste is in inverse proportion to the back pressure within a target time length, the target position is a position of a formation which is easy to leak in the oil and gas well, and the target time length is a time length when the gel strength of the cement paste reaches 240 Pa;
applying the back pressure to the annulus;
wherein the variation function of the density of the cement paste along with time is as follows:
and the ESD is the density of the cement paste, and t is the time length after the cement paste is injected into the annulus.
2. The method of claim 1, wherein determining a back pressure to be applied based on the real-time density of the cement slurry and a formation pressure equivalent density at a target location comprises:
detecting whether the time length of the cement slurry after being injected into the annulus is less than a target time length;
when the time length of the cement paste after being injected into the annulus is less than the target time length, calculating the back pressure to be applied by adopting a first back pressure calculation formula on the basis of the density of the cement paste at the current time and the formation pressure equivalent density at the target position; the first back pressure calculation formula is as follows:
wherein, P0For the back pressure to be applied, GpIs the formation pressure equivalent density, Δ G, at the target locationpIs a safe value of formation pressure equivalent density at the target location, H is a vertical height of cement slurry above the target location, t0Is the target duration.
3. The method of claim 2, wherein after detecting whether the elapsed time period after the cement slurry is injected into the annulus is less than a target time period, the method further comprises:
when the time length of the cement paste after being injected into the annulus is not less than the target time length, calculating the back pressure to be applied by adopting a second back pressure calculation formula on the basis of the density of the cement paste at the target time length and the formation pressure equivalent density at the target position; the second back pressure calculation formula is as follows:
4. the method of any of claims 1 to 3, wherein after applying the back pressure to the annulus, the method further comprises:
and after a specified time, stopping applying the back pressure to the annulus, wherein the specified time is the setting time of the cement paste.
5. The utility model provides a control device who exerts back pressure to annular space, its characterized in that is applied to when cementing the oil gas well, is located the accuse pressure equipment of wellhead of oil gas well, the device includes:
a first determination module for determining a real-time density of a cement slurry based on a function of a change in density of the cement slurry over time after running a casing in the well and injecting the cement slurry into an annulus between the well and the casing;
the second determination module is used for determining back pressure to be applied based on the real-time density of the cement paste and the formation pressure equivalent density at a target position, so that the real-time density of the cement paste is in inverse proportion to the back pressure in a target time length, and the target position is a position of a formation easy to leak in the oil and gas well, and the target time length is a time length when the gel strength of the cement paste reaches 240 Pa;
an application module for applying the back pressure to the annulus;
wherein the variation function of the density of the cement paste along with time is as follows:
and the ESD is the density of the cement paste, and t is the time length after the cement paste is injected into the annulus.
6. The apparatus of claim 5, wherein the second determining module is configured to:
detecting whether the time length of the cement slurry after being injected into the annulus is less than a target time length;
when the time length of the cement paste after being injected into the annulus is less than the target time length, calculating the back pressure to be applied by adopting a first back pressure calculation formula on the basis of the density of the cement paste at the current time and the formation pressure equivalent density at the target position; the first back pressure calculation formula is as follows:
wherein, P0For the back pressure to be applied, GpIs the formation pressure equivalent density, Δ G, at the target locationpIs a safe value of formation pressure equivalent density at the target location, H is at the target locationVertical height of square cement paste, t0Is the target duration.
7. The apparatus of claim 6, wherein the second determining module is configured to:
when the time length of the cement paste after being injected into the annulus is not less than the target time length, calculating the back pressure to be applied by adopting a second back pressure calculation formula on the basis of the density of the cement paste at the target time length and the formation pressure equivalent density at the target position; the second back pressure calculation formula is as follows:
8. the apparatus of any of claims 5 to 7, further comprising:
and the application stopping module is used for stopping applying the back pressure to the annular space after a specified time, wherein the specified time is the coagulation time of the cement paste.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911176664.2A CN111058794B (en) | 2019-11-26 | 2019-11-26 | Control method and device for applying back pressure to annulus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911176664.2A CN111058794B (en) | 2019-11-26 | 2019-11-26 | Control method and device for applying back pressure to annulus |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111058794A CN111058794A (en) | 2020-04-24 |
| CN111058794B true CN111058794B (en) | 2021-09-28 |
Family
ID=70298956
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911176664.2A Active CN111058794B (en) | 2019-11-26 | 2019-11-26 | Control method and device for applying back pressure to annulus |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111058794B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111535747B (en) * | 2020-05-09 | 2022-01-11 | 四川维泰科创石油设备制造有限公司 | Method for preventing leakage of casing under drilling narrow window |
| CN112253086B (en) * | 2020-10-15 | 2022-04-12 | 中国石油大学(华东) | Device and method for measuring initial acting force of well cementation |
| CN116163673B (en) * | 2023-04-25 | 2023-07-04 | 中国石油大学(华东) | Micro-pressure control device and method for deep water shallow gradient well cementation circulating wellhead |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1632279A (en) * | 2004-11-29 | 2005-06-29 | 西南石油学院 | Double action air leakage prevention agent for oil-gas well cementing, method for preparation and use thereof |
| CN101230778A (en) * | 2008-02-21 | 2008-07-30 | 四川石油管理局 | Technique of gas drilling post-infusion cement slurry |
| CN105298440A (en) * | 2015-10-27 | 2016-02-03 | 中国石油天然气股份有限公司 | Design method of well cementation annulus slurry column structure |
| CN108240196A (en) * | 2017-12-15 | 2018-07-03 | 中国石油集团川庆钻探工程有限公司 | The drilling liner cementing method of control pressure sensibility stratum annular equivalent density |
| CN109252828A (en) * | 2017-07-13 | 2019-01-22 | 中国石油天然气股份有限公司 | The cementing method of high angle hole |
Family Cites Families (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6910535B2 (en) * | 2002-11-15 | 2005-06-28 | Halliburton Energy Services, Inc. | Method for enhancing the stability of a water sensitive, reactive subterranean formation |
| CN101134892B (en) * | 2007-10-09 | 2011-11-09 | 中国石油大学(华东) | Deepwater well cementing mortar architecture |
| US8726993B2 (en) * | 2010-05-27 | 2014-05-20 | Claude E Cooke, Jr. | Method and apparatus for maintaining pressure in well cementing during curing |
| WO2012068006A2 (en) * | 2010-11-15 | 2012-05-24 | Shell Oil Company | System for controlling cement flow in a well |
| CN102539280B (en) * | 2010-12-10 | 2013-11-13 | 中国石油化工股份有限公司 | Temperature increasing and pressurizing foam cement slurry density testing device |
| US9249646B2 (en) * | 2011-11-16 | 2016-02-02 | Weatherford Technology Holdings, Llc | Managed pressure cementing |
| CN102877812A (en) * | 2012-09-14 | 2013-01-16 | 中国石油大学(华东) | Method of balancing pressure for well cementation |
| US8619256B1 (en) * | 2012-09-14 | 2013-12-31 | Halliburton Energy Services, Inc. | Systems and methods for monitoring the properties of a fluid cement composition in a flow path |
| CN103924944B (en) * | 2013-09-11 | 2017-01-18 | 华北石油管理局 | Well abandoning operation method for coal-bed gas horizontal wells |
| US10227836B2 (en) * | 2014-04-25 | 2019-03-12 | Weatherford Technology Holdings, Llc | System and method for managed pressure wellbore strengthening |
| MY187961A (en) * | 2014-12-10 | 2021-11-02 | Halliburton Energy Services Inc | Method for using managed pressure drilling with epoxy resin |
| US10787882B2 (en) * | 2015-01-23 | 2020-09-29 | Halliburton Energy Services, Inc. | Adaptive pressure relief valve set point systems |
| CN105332671B (en) * | 2015-10-27 | 2018-08-14 | 中国石油天然气股份有限公司 | A kind of process of high-pressure well well cementation |
| CN107843721B (en) * | 2016-09-19 | 2020-05-22 | 中国石油化工股份有限公司 | Evaluation device for cement paste weightless pressure and gas channeling prevention capability |
| CN108729901B (en) * | 2017-04-21 | 2022-05-06 | 中石化石油工程技术服务有限公司 | Method and device for keeping sealing integrity of cement ring |
| CN109723402A (en) * | 2017-10-30 | 2019-05-07 | 中国石油天然气股份有限公司 | A kind of casing pressure control well shaft fixing technology |
| CN109723403A (en) * | 2017-10-30 | 2019-05-07 | 中国石油天然气股份有限公司 | A kind of tail pipe pressure control well shaft fixing technology |
| CN108915635B (en) * | 2018-07-23 | 2021-07-06 | 中国石油集团川庆钻探工程有限公司 | Method for preventing gas channeling after cementing of high-pressure gas well tail pipe |
| CN109630062A (en) * | 2018-10-31 | 2019-04-16 | 中国石油集团川庆钻探工程有限公司 | A kind of fine pressure control well cementing operation method |
| CN109577954A (en) * | 2018-10-31 | 2019-04-05 | 中国石油集团川庆钻探工程有限公司 | Gu a kind of fine pressure control of complete integration of brill-survey-- is drilled well operations method |
-
2019
- 2019-11-26 CN CN201911176664.2A patent/CN111058794B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1632279A (en) * | 2004-11-29 | 2005-06-29 | 西南石油学院 | Double action air leakage prevention agent for oil-gas well cementing, method for preparation and use thereof |
| CN101230778A (en) * | 2008-02-21 | 2008-07-30 | 四川石油管理局 | Technique of gas drilling post-infusion cement slurry |
| CN105298440A (en) * | 2015-10-27 | 2016-02-03 | 中国石油天然气股份有限公司 | Design method of well cementation annulus slurry column structure |
| CN109252828A (en) * | 2017-07-13 | 2019-01-22 | 中国石油天然气股份有限公司 | The cementing method of high angle hole |
| CN108240196A (en) * | 2017-12-15 | 2018-07-03 | 中国石油集团川庆钻探工程有限公司 | The drilling liner cementing method of control pressure sensibility stratum annular equivalent density |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111058794A (en) | 2020-04-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111058794B (en) | Control method and device for applying back pressure to annulus | |
| WO2022105945A1 (en) | Method and system for managed pressure well cementing based on deep wellbore cement slurry system simulation | |
| WO2021082130A1 (en) | Acid fracturing simulation method considering variable-viscosity acid dynamic process | |
| CN105716998B (en) | A kind of computational methods of distress in concrete chemical grouting grout spreading range | |
| CA2946722C (en) | System and method for managed pressure wellbore strengthening | |
| Kunju et al. | Analysis of riser gas pressure from full-scale gas-in-riser experiments with instrumentation | |
| BR112020001111A2 (en) | methods and systems for automated cementation and liner suspension | |
| CN101710021A (en) | Detection device of physical property of natural gas supercritical flow state | |
| CN105626018A (en) | Determining method for starting time of well killing and well killing method | |
| CN114152554A (en) | Hydraulic shear stimulation hot dry rock reservoir permeability increasing simulation experiment system and experiment method | |
| CN211500608U (en) | Water lock injury physical simulation device | |
| CN106401523B (en) | A kind of blowout prevention cement mortar cementing method and device for high-temperature geothermal well | |
| CN115680584B (en) | Quick prediction method for well closing casing pressure of overflow medium for injecting water into adjacent well | |
| CN110874678B (en) | Method and device for determining highest operating pressure of underground gas storage | |
| CN114060018B (en) | Reservoir dynamic reserve determination method, system, equipment and readable storage medium | |
| CN109163964B (en) | Method and device for testing sleeve starting sliding sleeve | |
| EP3744417A1 (en) | Co2 recovery device and co2 recovery method | |
| CN109441432B (en) | Method for detecting circulating pressure loss of stratum drilling shaft with narrow safety density window | |
| CN108986579B (en) | The test method of crack of soils is induced when a kind of rehearsal for emergency flood fighting | |
| CN107965302B (en) | Driver and driver processing device and method | |
| WO2014148924A1 (en) | Improved effective well-bore diameter for heat extraction | |
| CN113006752B (en) | Method and device for predicting injection pressure | |
| CN114169204B (en) | Sand control opportunity determination method for offshore oil and gas field development and production | |
| CN114482916B (en) | Tail pipe controlled pressure weather coagulation construction parameter analysis method, device and medium with packer | |
| CN106774791A (en) | The method for drafting and device, user terminal of a kind of frame to be shown |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |