MX2012015250A - Processing of waters recovered in oil well reservoirs. - Google Patents

Abstract

The present invention is related to the industry for treating water so as to be recycled or removed under acceptable conditions. More particularly, this invention is related to a process for treating waters resulting from oil wells with hard-to-remove pollution. The advantages of the invention are that it removes most of the pollutants in congenital water; it is a compact plant useful for applying the aforementioned process, reducing the retention times and therefore the volume of the units; consuming low energy, using at the maximum extent the reactants and reducing the production of sludge and the disposal needs, also having a high efficiency, not requiring the retro-washing of filtration means nor the replacement thereof, or the constant addition of chemical products to remove heavy metals. Structurally, the invention comprises a dampening and roughing unit; a unit for the coagulation, flocculation and filtration in a sludge blanket, using a gravity filter of mixed bed, sand and an tracite, and a microelectrolysis unit.

Description

PROCESSING OF RECOVERED WATER IN DEPOSITS OF OIL WELLS FIELD OF THE INVENTION The present invention relates to the water treatment industry for recycling or for disposal under acceptable conditions. More specifically, it is related to a process of water treatment whose source is the oil grounds and that therefore has a contamination difficult to eliminate.

BACKGROUND OF THE INVENTION In the process of oil extraction, this carries with it congenital waters, which are separated and their disposal is necessary, this must be done in accordance with the particular norms and conditions of discharge fixed for each case in particular. The objective of the proposed treatment plant is to reduce the concentration of pollutants to the values established by the current norm.

Congenital wastewater is characterized by a high content of nest of dissolved and suspended solids, as well as free, emulsified and soluble oil, sulfuric acid, sulfides, and heavy metal content, all these contaminants outside the maximum discharge limits allowed by the Official Mexican Standard NOM-001-SEMARNAT- nineteen ninety six.

The disposal of water separated from oil extracted from deposits is and has been a serious problem to date, due to the adverse effects to the environment when it is available directly, without previous treatment or when it is injected into the reservoir to increase or maintain the production of oil, this due to the high content of emulsified oil and the content of suspended solids.

Traditionally, the separation of free oil takes place taking advantage of the density difference between oil and water, allowing the flotation of oil, however, this operation requires very large tanks.

For the removal of emulsified oil and suspended solids, some of the processes used to date refer to unit operations of coagulation, filtration, sedimentation and filtration, all these unit operations are carried out in separate units, so that they are generally extensive, unstable plants of treatment and with limited efficiencies for removal of emulsified oil and suspended solids. Recently, since the nineties, ultrafiltration units with membranes have been used, however, this process has great disadvantages such as its high investment cost, very strict pre-treatment requirements, as well as strict requirements for the cleaning of the membranes. Another process used is cyclone separation, although it is a low cost process, it does not achieve the efficiencies of emulsified oil removal and suspended solids necessary for its injection or disposal.

Some of the processes used for the removal of heavy metals are their precipitation either as hydroxides, sulphides or sulfates and as carbonates, however these processes require particular conditions for each element, which makes the process difficult, as well as the The formation of precipitated sludge is usually greater, making it difficult to manage and increasing costs due to reagents and sludge disposal.

In the state of the art, Mexican documents are known that deal in one way or another with congenital water. For example, patent document MX PA06015020 discloses a corrosion inhibitor-scale additive to be used in the treatment of congenital waters obtained by the dehydration processes of crude oils that leave the exploitation wells at a high temperature. ra environment. This invention does not completely solve the problem of congenital waters since contaminants still exist in water.

The Mexican patent document P A06015021 discloses a composition of bactericidal additive to be used in the treatment of congenital waters obtained in the process of dehydration of crude oils leaving the exploitation wells. It is the same situation as in the previous document.

The Mexican patent document P A2010004511 discloses a chelating composition that allows to obtain congenital water with a lower hardness for its use in injection wells and contribute to solving the problem of scale in pipes and equipment of a congenital water treatment plant. As you can see, this procedure is aimed at solving only one of the multiple problems presented by the treatment of congenital waters.

Finally, Mexican patent document 2011 010713 discloses a process consisting of 10 stages: 1) fine screening, 2) homogenization, equalization and flow regulation, 3) pH adjustment. 4) electro-flocculation and / or electrocoagulation and / or high impact ionization, 5) primary re-pumping, 6) clarification, 7) sludge treatment, 8) advanced oxidation, 9) filtration system and 10) osmosis reverse sis. This is an expensive process due to the inclusion of a unit operation involving a membrane (reverse osmosis) device and very complicated when using 10 operations in the process.

From this state of the art we can see that it is still required processes that are simple, without much use of energy, to reduce the carbon footprint, and ingenious equipment in which the stoppages for maintenance are the minimum.

OBJECTIVES OF THE INVENTION The main objective of the present invention is to achieve a water treatment process that manages to eliminate most of the contaminants to a congenital water.

Another objective of the invention is to achieve a compact plant that applies the process indicated in the previous paragraph, reducing the retention times and therefore the volume of the units.

Still another objective is to provide the plant of the previous objective the quality of consuming little energy, making the most of the occupied reagents and reducing the production of sludge and the needs for their disposal.

Still another objective of the present invention is to increase the efficiency, not require the retro-washing of the filtering media or its replacement or require the constant addition of chemical products for the removal of heavy metals.

And all those objectives and advantages that will become apparent with the reading of the present description accompanied by the figures that are an integral part of it, and that are annexed for illustrative but not limitative purposes.

BRIEF DESCRIPTION OF THE INVENTION In short, the present invention consists, in one of its aspects, in a congenital water treatment process, composed of several unitary operations that are generally known, but which in particular have specific characteristics and are included in a single process. and concatenated in a precise way.

In another of its aspects, the present invention consists of a team that applies the indicated process.

The proceeding comprises different unit operations, each one of them to reduce and adjust the content of contaminants below what is established as the maximum permissible in the current regulations, then and in the direction of flow is a description of the proposed processes and units The proposed treatment plant involves different processes, each of them to reduce and adjust the content of contaminants below the established maximum permissible in the current regulations, then and in the direction of flow is a description of the processes and proposed units As a first stage, a tank is proposed to dampen the influent water and for roughing, separating most of the free oil, also to eliminate the sulfhydric and reduce the content of sulfides, the above with a process of aeration, for the purpose the unit It has a blower to inject air into the tank through a system of thin pore membrane diffusers, circular diffusers with a diameter of 9 inches.

As a second stage, the processes of coagulation, flocculation, filtration in sludge mantle and water purification in modules for sedimentation in high rate are proposed. These processes are carried out in a single unit, which we will call "Filtration" in Manto de Lodos "(FML) The effluent from the FML unit is conducted to a gravity filter with mixed medium of anthracite sand to reduce the content of suspended solids and oil in the water in the treatment condition necessary to pass to the process of reduction of heavy metals with micro electrolysis .

The filtered effluent passes to an intermediate balance tank from where the water is fed to the micro electrolysis process for the removal of heavy metals.

The micro-electrolysis consists of an operation where numerous small galvanic cells are formed with the help of the difference of electrical potential between iron and carbon particles. These small galvanic cells take the low potential of iron as cathode and the high potency of carbon as the anode. When the electrochemical reaction is carried out in an aqueous solution containing acidic electrolyte, the iron corrodes and transforms into ferrous ions and dissolves in the medium. The internal water of the electrolytic reactor requires an adjustment to a pH of around 9, since the iron ion reacts with the hydroxyl to form a coagulating ferrous hydroxide, this ion attracts the particles of opposite polarity, which have a slight negative charge in contaminants, and forms relatively stable flocs. To increase the potential difference and promote the release of ions, proportional lead and copper powder is added to the bed of ferric-carbon, or a certain amount of hydrogen peroxide is added, to generate the Fenton reaction which has a powerful oxidation ability. Due to the above, very desirable micro-electrolysis for high concentrations and strongly degradable acid waste waters In its aspect of equipment, the present invention consists of the following to reduce and adjust the content of contaminants below the established maximum permissible in the current regulations, then and in the direction of flow is a description of the proposed processes and units.

• As a first stage, a tank is proposed to dampen the influent water and for roughing, separating the largest part from the free oil, as well as to eliminate the sulfuric acid and reduce the content of sulfides, the above with a process of aeration, for the effect the unit has a blower to inject air into the tank through a system of thin pore membrane diffusers, circular diffusers with a diameter of 9 inches.

• As a second stage, the processes of coagulation, filtration, filtration in sludge mantle and water purification in modules for high rate sedimentation are proposed. These processes are carried out in a single unit, which we will call as unit for " Filtration in Sludge Mantle "(FML). The processes of coagulation and flocculation involve the addition of chemicals a coagulant (aluminum polychloride) and a polymer (polyacrylamide). Likewise, within this same unit the separation of excess sludge and its concentration is carried out to facilitate its subsequent disposal.

• The effluent of the FML unit is conducted to a gravity filter with mixed medium of anthracite sand to reduce the content of suspended solids and oil in the water in the necessary treatment condition to pass to the process of reduction of heavy metals with micro electrolysis.

• The filtered effluent passes to an intermediate balance tank from where the water is fed to the process of micro electrolysis for the removal of heavy metals. This tank also has the function of storing water necessary for the backwash of the filtration and micro electrolysis units.

• Finally the water passes to the micro electrolysis unit, where the heavy metal reduction process is carried out, the unit has a medium with elements whose electric potential difference form small and numerous galvanic cells where the iron with its low potential works as a cathode and high potential carbon works as an anode, this medium in aqueous solution corrodes the iron forming ferrous ions that they enter the solution that in the presence of oxygen a hydroxide is formed as an active coagulant that sequesters the heavy metals.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 illustrates the scheme of the unit for damping and roughing.

Figure 2 illustrates the scheme of the unit for filtration in sludge blanket.

Figure 3 schematizes the mixed bed gravity filter.

Figure 4 illustrates a schematic of the intermediate balance tank.

Figure 5 schematizes the unit for micro electrolysis Next, the best way to carry out the present invention will be described and described, by means of a modality thereof, although of course there may be modalities thereof.

DETAILED DESCRIPTION OF THE INVENTION The first problem to be resolved was the definition of the treatment needs required for congenital waters, based on the general characteristics of congenital waters and that established by the corresponding environmental regulations.

Once the treatment needs were defined, the processes required for the reduction of contaminants or parameters outside the established regulations were selected and, of course, with the premise of minimizing the adverse effects to the environment.

Once the processes involved were defined, the design of the experimentation would be needed to obtain the design parameters of each of the units, such as flows, retention times, surface loads, velocity gradients, definition of chemical reagents and their respective dosages. , efficiencies of removal of each and every one of the parameters or contaminants present.

The first unit operation of the congenital water treatment process taught in the present invention consists of the regulation of the inflow to the plant, as well as the separation of the free oil, the elimination of hydrogen sulfide and the reduction in the sulfide content.

All this, in one embodiment of the present invention, is carried out in a tank for damping and roughing as illustrated in Fig. 1, where the waste water is fed to the vertical cylindrical tank (1) by a pipe (2). ) of feeding, in which the meter of the flow of water fed to the plant is installed. To promote a better separation of oil, as well as the dragging of sulfuric acid and oxidation of sulfides, the unit has a system for air injection consisting of a blower (5), air pipe (6) and a diffuser system (7). ) of fine pore membrane, the separated oil on the surface is collected by a peripheral channel (8) and discharged by a pipe (9). The effluent water is conducted by pipe (3) to a pump (4) who sends it to the Sludge Filtration unit, for purging and cleaning the buffer tank, the drain valve 10 is available.

The next operation, whose main function is the removal of suspended solids and soluble and emulsified oil, as well as the concentration of separated solids, this through the processes of coagulation, flocculation, filtration in sludge mantle and separation of solids in inclined plates.

The addition of coagulants and flocculants is done in a simultaneous and its effect is carried out controlling the vigor of the agitation, being more energetic for coagulation and less energetic for flocculation. The filtration is carried out in an almost laminar regime due to the effect of communicating vessels.

The equipment that carries out these operations consists of a vertical cylindrical tank (11) that operates at atmospheric pressure, whose components as a whole, described in the direction of flow through the unit are: A static mixer (12) placed in the line that feeds the unit, with pipes (13) that feed the reagents for coagulation and flocculation, once the reagents are added, the water passes to a conduit (14) where the coagulation process begins, this conduit discharges into a cone (15) where the flocculation process is developed, the movement that promotes the agglomeration of particles for the formation of floc-els is favored by the downward flow of the water under treatment and is supported by a mechanical agitator (18), the The agitator in turn avoids the sedimentation of solids in the bottom of the cone, the solids and the water in treatment ascend along the periphery of the co-no, remaining in the zone between the cone and the walls of the t However, where the surface area is increasing and therefore the influence of the agitator decreases, the sludge remains in this area forming a layer or mantle of mud (16) the water in treatment is filtered as it passes through it. layer or mantle of mud.

The excess sludge exits through a spout (17) and is collected by a peripheral gutter (28) inside the tank, the water after passing through the mud mantle ascends passing through a section of tubular modules (19) for the retention of small amounts of solids dragged by the rising water, the treated water, free of solids, is collected by a peripheral spout and gutter (20) and discharged by an effluent pipe (24) The sludge collected in the gutter for excess sludge (28) is extracted and conducted through a pipe (21) to the sludge concentration zone (22) with a section with hopper function (23) to facilitate the handling and extraction of sludge. the sludge by means of a pipeline for extraction of concentrated sludge (26), the supernatant water separated from the sludge is drained by the pipe (25) for supernatant, the zone for concentration of sludge also has a pipe for expulsion of air ( 27).

The next unit separation operation, which allows to finish removing the suspended solids and the oil dragged with the effluent from the Filtration unit in Slurry Mantle For this unit operation, there is a device as shown in Figure 3, the filter is a vertical cylindrical tank (31) operating at atmospheric pressure, water from the buffer tank is fed (32) by gravity in the upper part of the filter, to avoid disturbances in the medium, the unit has a dissipating plate (33), water it passes through the filter media, anthracite (34) and sand (35) and is captured by jets (36) that leads them to the lower part or under drain from where they are extracted by the outlet pipe (37) and the pump for feeding the intermediate balance tank.

The intermediate balance tank, in turn, has no effect on the water that is being treated, and its function is to store water for the backwashing of both the filter and the micro electrolysis unit, as well as to allow an extraction of water for the micro electrolysis unit.

As can be seen in Figure 4, the tank is of vertical cylindrical shape (41) the influent pipe (42) discharges into the upper part of the tank, the unit has a pipe socket for retro-washing the filter (43) and the respective pump (44), likewise pipe (47) for the backwashing of the micro electrolysis unit and the respective pump (48), likewise has the intake and pipe (45) to feed the water to the micro electrolysis unit with its respective pump (46).

The last operation in water treatment is the micro- electrolysis, operation that allows to reduce the content of heavy metals to the values of concentrations established by the authorities.

The equipment for this operation is schematized in Figure 5 and consists of a tank that is cylindrically vertical (51) the influent pipe (52) enters the top of the tank and passes through the micro electrolysis medium (53). ) which is supported by a perforated plate (54) that allows the passage to the low drain from where the treated water comes out (55), the unit also has pipes for the entrance (57) and exit (56) of retro water -washed.

As can be seen in the description in conjunction with the appended figures that form an integral part of the present description, this association of equipment results in a compact plant that requires smaller spaces, conventional plants and processes use separate units for each one of the processes, in our case we use the same unit for process processes, which significantly reduces the necessary space and also contributes to lower investment costs.

Lower energy consumption than conventional treatments, conventional plants that require more process units and therefore equipment have a higher energy consumption lower operating and maintenance costs, therefore having less operating units needs and operation and maintenance costs are lower.

They also give the plants that reproduce these teachings a stable, reliable operation with greater efficiencies in the removal of contaminants.

Although the selected processes are open technology, the set of operations involved in the treatment plant as well as its sequence and specific applications are unique and therefore its use in the way we consider this proposal as innovative.

The invention has been described sufficiently so that a person with average knowledge in the field can reproduce and obtain the results that we mentioned in the present description. However, any person skilled in the field of the art who is responsible for the present invention may be able to make modifications not described in the present application, however, if for the application of these modifications in a certain structure or in the process of manufacturing thereof, the subject matter claimed in the following claims is required, said structures should be understood within the scope of the invention.

Claims (10)

R E I V I N D I C A C I O N S Having described the invention is considered as a novelty and is therefore claimed as a novelty, contained in the following claims.

1. Processing of reclaimed water in wells pe-troleros characterized by understanding as the first operation the separation of most of the free oil, the sulfide that could contain and reduction of the sulfides by means of a process of air bubbling; then, the water resulting from the previous operation is subjected to four consecutive processes, coagulation, flocculation, filtration in mud mantle and sedimentation in high rate; effluents from these operations are immediately followed by gravity filtering in a sand and anthracite filter where the content of suspended solids and the entrained oil is decreased; To the water that passed the sand and anthracite filter, the micro-electrolysis operation is applied to a bed of iron and carbon particles.

2. Processing of recovered water in tanks of oil wells, as claimed in the preceding claim, further characterized because for the coagulation operation, the water to be treated with the coagulant and the flocculant receives a vigorous agitation and for the flocculation operation this water receives a quieter agitation.

3. Processing of reclaimed water in tanks of oil wells, as claimed in claim 1, further characterized in that said air bubbling is a fine bubble bubbling.

4. Equipment for the processing of reclaimed water in oil well deposits characterized by comprising a unit for cushioning and roughing; then a unit for coagulation, flocculation and filtration in mud mantle; with a sand and anthracite mixed bed gravity filter and a micro electrolysis unit.

5. Equipment for the processing of recovered water in tanks of oil wells, as claimed in the preceding claim, further characterized in that between the gravity filter and the micro-electrolysis unit an intermediate balance tank is provided.

6. Equipment for processing reclaimed water in tanks of oil wells, as claimed in claim 4, further characterized by said unit for damping and roughing comprises vertical cylindrical (1) by a pipe (2) of power, which is installed the water flow meter fed to the plant. To promote a better separation of oil, as well as the dragging of sulfuric acid and oxidation of sulfides, the unit has a system for air injection consisting of a blower (5), air pipe (6) and a diffuser system. (7) Fine pore membrane, oil separated on the surface is collected by a peripheral channel (8) and discharged by a pipe (9). The effluent water is piped (3) to a pump (4) who sends it to the Sludge Mantle filtration unit.

7. Equipment for the processing of reclaimed water in tanks of oil wells, as claimed in claim 4, further characterized in that said unit for coagulation, flocculation and filtration in sludge mantle comprise a static mixer (12) placed in the line that feeds to the unit, with pipes (13) that feed the reagents for coagulation and flocculation, once the reagents are added, the water passes to a duct (14) where the coagulation process begins, this duct discharges into a cone (15) in where the flocculation process is developed, the movement that propitiates the agglomeration of particles for the formation of larger flocs is favored by the downward flow of the water under treatment and is supported by a mechanical agitator (18), the agitator in turn avoids sedimentation of solids at the bottom of the cone, the solids and the water under treatment rise along the periphery of the cone, remaining in the zone between the cone and the walls of the tank where the surface area is increasing and therefore the influence of the agitator decreases, the sludge remains in this area forming a layer or mantle of sludge (16) the water in treatment is filtered in its passage through this layer or mantle of mud.

8. Equipment for processing reclaimed water in tanks of oil wells, as claimed in claim 4, further characterized in that said gravity filter is a vertical cylindrical tank (31) operating at atmospheric pressure, the water coming from the tank to damping is fed (32) by gravity in the upper part of the filter, to avoid disturbances in the medium, the unit has a dissipating plate (33), the water passes through the filtering media, anthracite (34) and sand ( 35) and it is captured by jets (36) that leads them to the lower or lower drain from where they are extracted by the outlet pipe (37) and the pump to feed the intermediate balance tank.

9. Equipment for the processing of recovered water in oil well depots, as claimed in the claim 4, further characterized in that said micro-electrolysis unit consists of a tank that is of vertical cylindrical shape (51) the influent pipe (52) enters from the top of the tank and passes through the micro electrolysis means (53) the which is supported by a perforated plate (54) that allows the passage to the low drain from where the treated water comes out (55), the unit also has pipes for the inlet (57) and outlet (56) of backwash water.

10. Equipment for processing reclaimed water in oil well deposits, as claimed in claim 5, further characterized in that said buffer tank consists of a vertical cylindrical tank (41), the influent pipe (42) discharge in the upper part of the tank, the unit has a pipe socket for the retro-wash of the filter (43) and the respective pump (44), likewise pipe (47) for the back-washing of the micro unit electrolysis and the respective pump (48), likewise it has the outlet and pipe (45) to feed the water to the micro electrolysis unit with its respective pump (46). SUMMARIZES The present invention relates to the water treatment industry for recycling or for disposal under acceptable conditions. More specifically, it is related to a process of water treatment whose source is the oil grounds and that therefore has a contamination difficult to eliminate. The advantages are that it manages to eliminate most of the contaminants to a congenital water; is a compact plant that applies the process indicated in the previous paragraph, reducing the retention times and therefore the volume of the units; it consumes little energy, taking full advantage of the occupied reagents and decreasing the production of sludge and the needs for its disposal and has a high efficiency, it does not require the retro-washing of the filtering media nor its replacement nor does it require the constant addition of chemical products for the removal of heavy metals. Structurally it includes a unit for damping and roughing; then a unit for coagulation, filtration and filtration in sludge blanket; with a sand and anthracite mixed bed gravity filter and a micro electrolysis unit.