GB2297571A - Well logging and control system - Google Patents

Abstract

A down-hole data logging system for use with an electrical submergible pump or ESP (7) allows information to be obtained on the production characteristics of a plurality of producing zones (1,2,3) and/or regions within a zone or zones of an oil well. The system includes production tubing (6) depending within said well into said producing zones (1,2,3) equipped with isolation means (4) to prevent flow of fluid between or within producing zones (1,2,3). Flow communicating means within each of said producing zones allows fluid from each said zone to be channelled into said production tubing, whilst measuring means (5) monitors production characteristics of said fluid from each of said zones (1,2,3).

Description

WELL-LOGGING AND CONTROL SYSTEM The present invention relates to a well-logging and control system particularly, although not exclusively, for use with an electrical submergible pump.

It is common practice for oil wells to be drilled so as to traverse a multitude of oil bearing zones and for production of oil to be obtained from these zones simultaneously. Similarly it is-common practice for an Electrical Submergible Pump to be used to provide artificial lift to raise the produced oil to the surface.

Production rates from individual zones may vary from each other at commencement of production and may change during the producing period such variation may also occur within a zone, particularly where the zone is very thick. Furthermore the fluid produced may be a mixture of oil and water, the relative quantities of which may also vary during the producing period.

The variations in production rates and fluid mixture (oil/water ratio) from individual areas of the well may be determined by wireline logging below the Electrical Submergible Pump (ESP) using standard wireline techniques whereby logging tools (gauges) are deployed below the ESP via a by-pass tube, allowing measurements to be taken whilst the ESP is operational.

In wells where access below the ESP is restricted it is common practice to install permanent monitoring devices to provide an overall analysis of the well conditions. These permanent gauges are fixed in position and cannot therefore give detailed information of conditions at individual producing zones.

It is an aim of the present invention to provide detailed information of production characteristics for individual producing zones using permanently installed monitoring devices. The requirements of the monitoring system may vary with and/or be restricted by individual well geometry and to this end alternative installation diagrams showing monitoring and well control systems are included.

According to a first aspect of the present invention there is provided a down hole data-logging system for use with an electrical submergible pump in order to obtain information on production characteristics of a plurality of producing zones within an oil well comprising, production tubing depending within said well into said producing zones, isolation means for preventing flow of fluid between adjacent producing zones, flow communicating means within each of said producing zones to enable fluid from each said zone to be channelled into said production tubing, and measuring means for monitoring the production characteristics of each of said zones.

Preferably, said isolation means comprises a set of collars or pack-off devices each secured to said production tubing between respective production zones.

Still preferably, the measuring means forms part of said flow communicating means such that the production characteristics are continuously monitored at each of said zones.

Alternatively, the measuring means may preferably communicate with said production tubing immediately above said producing zones, in which case each of said flow communicating means is provided with a shut off valve to facilitate monitoring of production characteristics from a selected one or ones of said zones.

Where a well contains a production zone which is very thick, the invention may be applied to obtain information on production characteristics from one or more regions within said zone.

Hence, according to a second aspect of the invention there is provided a down-hole data logging system for use with an electrical submergible pump in order to obtain information on production characteristics in regions of a producing zone within an oil well comprising, production tubing depending within said well into said producing zone, isolation means for preventing flow of fluid between regions of said producing zone, flow communicating means within each of said regions to enable fluid from each said region to be channelled into said production tubing, and measuring means for monitoring production characteristics of said fluid from each of said regions.

Preferably, said isolation means comprises a set of packoff devices each secured to said production tubing within said production zone.

Still preferably, the measuring means forms part of said flow communicating means such that said production characteristics of said fluid are continuously monitored at each of said regions.

Alternatively, the measuring means may communicate with said production tubing immediately above said producing zone, in which case each of said flow communicating means is provided with a shut-off valve to facilitate monitoring of said production characteristics from a selected one or ones of said regions.

Figure (1) describes a completion whereby a permanent monitoring device such as the Multi-Sensor described in our U.S. Patent No. 5,213,159 and European Patent No. 0465543, is attached directly below the ESP motor section in order to measure a number of parameters. Typically these parameters would include the intake and discharge pressures of the ESP pump, the produced fluid and ESP motor temperatures and vibration of the ESP Assembly.

The diagram shows three producing zones (1,2,3) separated by pack-off devices or isolation collars (4) which constitute a barrier preventing migration of fluid from one producing zone to another. Fluid flowing from a zone passes through a monitor (5) equipped with facilities for establishing the total flow rate from the zone together with measurement of the oil/water ratio of the produced fluid. The equipment is configured such that produced fluid from zone 3 shown on the diagram passes through the monitoring equipment (5) and zone isolation collar (4) and is then transported via standard oilfield tubulars (6) to an ESP (7) above. Fluid produced from zone 2 enters a similar monitor (5) to that positioned at zone 3 wherein the fluid produced from zone 2 is similarly assessed before being combined with the fluid produced from zone 3.The combined produced fluids from zones 2 and 3 are then transported via standard oilfield tubulars (6) to the ESP (7) above. The fluid produced from zone 1 is similarly assessed for flow rate and oil/water ratio before combining with the combined produced fluids from zones 2 and 3. The total combined produced fluid from zones 1, 2 and 3 from there flow into the well casing via a flow sub (8) and past a permanent downhole gauge (Multi-Sensor) (9) at which point other parameters, including but not restricted to pressure and temperature, may be measured.

The produced fluid then enters the pump (7) and is transported to surface via discharge head (28) into production tubing (10). A monitor (5) assessing the total combined flow rate and oil/water ratio together with other parameters including but not restricted to pressure and temperature may be included within this production tubing above the ESP (7) motor (12) to confirm the values measured by the individual monitors positioned at the individual zones.

The statistics provided by all the monitoring systems at individual zones and optionally in the production tubing are collected and processed at the Multi-Sensor (9) and from there transmitted to surface as described in the aforementioned Multi-Sensor patent specification or by other suitable means.

The system detailed and described in Figure (1) is applicable in wells where the distances between producing zones are short and where pressure differentials between the zones are small. In wells where the zone intervals are large and/or where large pressure differentials occur a completion as described in Figure (2) will provide more detailed well analysis.

Figure (2) illustrates a well with multiple producing zones (1,2,3) each of which is equipped with a permanent monitor (Multi-Sensor) (9) capable of recording parameters including but not restricted to pressure, temperature, flow rate and oil/water ratio. The well casing (11) between each zone (1,2,3) is sealed by a zone isolation collar (4) such that flow from a zone must pass through the permanent monitor (5) for analysis before entering standard oilfield tubulars (6) for transportation to the ESP (7).

The diagram shows the completion of a well with three producing zones. Produced fluid from zone 3 is monitored prior to passing through the zone isolation collar (4) into the standard oilfield tubular (6) for transportation to the ESP (7). Produced fluid from zone 2 is similarly monitored prior to combining with the produced fluid from zone 3 and entry into the standard oilfield tubular (6) for transportation to the ESP (7). This process is repeated at zone 1 where produced fluid from that zone is monitored prior to combining with produced fluids from zones 2 and 3. The combined fluids in the three zones flow into the casing (11) via a flow sub (8) and pass a further Multi-Sensor (9) where parameters including but not restricted to pressure and temperature may be measured before the combined produced fluids enter the pump (7) and are transported to surface.

As in Figure (1) a monitor (not shown) may be positioned within the production tubing (10) above the ESP (7) to access the total combined flow rate and oil/water ratio together with other parameters including but not restricted to pressure and temperature. Statistics provided by this monitor are collected and processed by the Multi-Sensor (9) positioned immediately below the ESP motor (12) for transmission to the surface as described in the aforementioned Multi-Sensor Patent or by other suitable means.

This Multi-Sensor and those situated at the individual zones are electrically connected and disconnected in turn, enabling data from all Multi-Sensors to be transmitted to surface via the same route. Such connection and disconnection of the individual Multi-Sensors is performed by automatic or manually selected instruction from the surface via the same data transmission route.

The completions described in Figures (1) and (2) detail facilities for monitoring flow from individual producing zones. The control of flow from individual zones will allow the well operator to optimise production from this more efficient well zones whilst preventing production from uneconomic zones.

Figure (3) describes a well completion whereby the flow from any or all producing zones (1,2,3) may be controlled without the necessity of retrieving the ESP (7) to surface to permit access to the well bore adjacent to the producing zones. In the completion described in Figure (3) the well bore adjacent to each producing zone (1,2,3) is isolated from other areas by the installation of a zone isolation collar (4) above and below the producing zone.

It can be seen from - the diagram that flow from the individual zones enters standard oilfield tubulars (6) via a shut-off valve (13).

Produced fluid from all zones (1,2,3) is monitored by monitoring device (5) for parameters including but not restricted to flow rate and oil/ water ratio at a point above the top zone isolation collar (4) and before entering the casing (11) annulus via a flow sub(8).

As in Figures (1) and (2) the combined produced fluid may then be subjected to further analysis by a Multi-Sensor (9) positioned immediately below the ESP motor (12) and a monitoring device (not shown) located within the production string above the ESP.

It can be seen that the closure of the shut-off valve (13) at zone 3 will allow analysis of the combined fluids from zones 1 and 2. The analysis, when compared with analysis of the combined fluids from all three zones, will enable computation of the flow rate and oil/water ratio of the produced fluid from zone 3. Similarly the closure of the shut-off valve (13) at either zone 1 or zone 2 will allow computation of the flow rate and oil/water ratio of the fluid produced from that zone. Alternatively two shut-off valves (13) may be closed allowing direct measurements to be taken of the fluid produced from the remaining producing zone.

The closure and opening of the shut-off valves (13) is performed hydraulically, the required hydraulic power being obtained by tapping into the production string above the ESP pump (7). Switching of the hydraulic power to individual valves (13) is performed electrically, either automatically or by selective control, from the surface via the route used for transmission of data to the surface.

The zone isolation collars (4) may also be manipulated using the hydraulic power available from the ESP pump (7) discharge to ensure adequate isolation of individual zones, regardless of the type of completion. Similarly, the type and positioning of monitoring systems shown in Figures 1 and 2 may be used incorporating shut-off valves at each producing zone.

Figure 4 which shows a side elevation of part of a completion in partial axial section, displays in greater detail one possible embodiment, wherein a monitoring device (5) is positioned between two isolation collars (4) situated in the well casing (11) such that sealing elements (14) prohibit movement of fluids produced from the producing zone (Z) along the casing (11). Fluid from the producing zone is consequently directed through apertures (15) and (16) to combine with flow from lower producing zones in the production tubing bore (17).

The monitoring device (5) is itself supported between the isolation collars (4) by production tubings (6) which may be variable in length to facilitate the length of the producing zone pertaining in a particular well. The monitoring device (5) is constructed so as to accommodate sensors including, but not restricted to, a flow meter (18). fluid density meter (19), pressure sensor (20) and temperature sensor (21). The monitoring device (5) consists of a housing (22) and cover (23) such that an atmospheric chamber (24) is protected from well fluids by sealing elements (25) and (26). Electronic circuitry (not shown) is located within the atmospheric chamber (24) and is connected directly or indirectly to the surface via a cable (27) whereby the data monitored by the meters/sensors housed within the monitoring device (5) and connected to the circuitry may be transmitted to surface. The cable (27) passes through the isolation collar (4) above the monitoring device (5) using conventional means and is extendible to pass through the isolation collar (4) below in similar manner (not shown) to connect to a similar monitoring device (not shown) in a lower producing zone.

It will also be understood that various alterations and modifications may be made to the above embodiments to suit different well geometries without departing from the scope of the invention, and in particular the invention may be applied to wells having particularly thick production regions. In which case, the arrangement of isolation collars and monitoring devices may be such as to allow production characteristics of various regions within a'production zone to be determined in a similar manner to that described in the above embodiments relating to a plurality of production zones.

Claims (10)

CLAIMS:

1. A down-hole data logging system for use with an electrical submergible pump in order to obtain information on production characteristics of a plurality of producing zones within an oil well comprising, production tubing depending within said well into said producing zones, isolation means for preventing flow of fluid between adjacent producing zones, flow communicating means within each of said producing zones to enable fluid from each said zone to be channelled into said production tubing, and measuring means for monitoring production characteristics of said fluid from each of said zones.

2. A system according to Claim, wherein said isolation means comprises a set of pack-off devices each secured to said production tubing between respective production zones.

3. A system according to any preceding Claim, in which the measuring means forms part of said flow communicating means such that said production characteristics of said fluid are continuously monitored at each of said zones.

4. A system according to Claim 1 or Claim 2, in which said measuring means communicates with said production tubing immediately above said producing zones, and each said flow communicating means is provided with a shut-off valve to facilitate monitoring of said production characteristics from a selected one or ones of said zones.

5. A down-hole data logging system for use with an electrical submergible pump in order to obtain information on production characteristics in regions of a producing zone within an oil well comprising, production tubing depending within said well into said producing zone, isolation means for preventing flow of fluid between regions of said producing zone, flow communicating means within each of said regions to enable fluid from each said region to be channelled into said production tubing, and measuring means for monitoring production characteristics of said fluid from each of said regions.

6. A system according to Claim 5, wherein said isolation means comprises a set of pack-off devices each secured to said production tubing within said production zone.

7. A system according to Claim 5 or Claim 6, in which the measuring means forms part of said flow communicating means such that said production characteristics of said fluid are continuously monitored at each of said regions.

8. A system according to Claim 5 or Claim 6, in which said measuring means communicates with said production tubing immediately above said producing zone, and each said flow communicating means is provided with a shut-off valve to facilitate monitoring of said production characteristics from a selected one or ones of said regions.

9. A down-hole data logging system for use with an electrical submergible pump substantially as described herein with reference to Figure 1 or Figure 2 or Figure 3 or Figure 4 of the accompanying drawings.

10. The features herein described or illustrated, or their equivalents, in any patentably novel selection.