METHOD OF INJECTION FLUID MONITORING
A method of monitoring an injection substance injected into an injection well penetrating the earth and a method of monitoring an underground reservoir storing a substance introduced through an injection well are described. The methods include disposing a monitoring system in a borehole, both a transmitting and a first receiving portion of the monitoring system being disposed in the borehole. The method of monitoring an injection substance also includes injecting the injection substance into the injection well, and monitoring, using a processor processing the received signal, flow of the injection substance out of the injection well. The method of monitoring an underground reservoir includes injecting the injection substance into the injection well for storage in the underground reservoir, and monitoring, using a processor processing the received signal, boundary conditions surrounding the underground reservoir.
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This application is a Non-Provisional Application of U.S. Provisional Application No. 61/746,180 filed Dec. 27, 2012, the disclosure of which is incorporated by reference herein in its entirety.
BACKGROUNDInjection wells are used for various purposes in the drilling industry. As one example, injection fluid (e.g., water, CO2) may be injected through the injection well toward a producing well (producing oil, for example) to increase pressure and thereby encourage production. However, once the injection fluid front reaches the production well such that the injection fluid is being produced, the production well is no longer viable. Prior systems to monitor injection fluid have been disposed in the production well or one or more monitor wells (separate from the production well and injection well) or some combination thereof. The systems obtain resistivity or conductivity (inversely proportional to resistivity) measurements around the borehole in which they are located and can determine the boundary between materials that have discernibly different resistivity values (e.g., the boundary between a production fluid like oil and an injection fluid like water). When such a system is located in the production well or in a monitor well in the vicinity of the production well, it indicates when the fluid front from the injection well has reached or nearly reached the production well. However, the information is not timely enough to control the injection process to potentially prolong the use of the production well. Prior methods of monitoring are also problematic because the injected fluid may not necessarily reach the production well due to heterogeneity and/or permeability anisotropy around the injection well. In this case, the direction and flow rate from the injection well is unknown. Another exemplary purpose of an injection well is for the introduction of material into an underground storage reservoir. In this case, the seal on the storage reservoir must be monitored to ensure that the stored material is not leaking into the surrounding area.
SUMMARYAccording to an aspect of the invention, a method of monitoring an injection substance injected into an injection well penetrating the earth includes disposing a monitoring system in a borehole, both a transmitting and a receiving portion of the monitoring system being disposed in the borehole; injecting the injection substance into the injection well; and monitoring, using a processor processing the received signal, flow of the injection substance out of the injection well.
According to another aspect of the invention, a method of monitoring an underground reservoir storing a substance introduced through an injection well includes disposing a monitoring system in a borehole, both a transmitting portion and a receiving portion of the monitoring system being disposed in the borehole; injecting the injection substance into the injection well for storage in the underground reservoir; and monitoring, using a processor processing the received signal, boundary conditions surrounding the underground reservoir.
Referring now to the drawings wherein like elements are numbered alike in the several Figures:
As noted above, prior injection monitoring systems have been positioned in the production well or in monitor wells near the production well. An exemplary injection arrangement positions a number of injection wells surrounding the production well. The injections wells may even be essentially equidistant from the production well, and each injector may even inject the injection fluid at the same rate. However, inhomogeneity in the reservoir may render the injection system inhomogeneous (injection fluid from each injection well reaches the production well at a different time or not at all). For example, the injection fluid front from a given injection well may be advancing toward the production well faster than the injection fluid front from any of the other wells. If this were determined early in the injection process, the given injection well may be choked off to increase the time until an injection fluid front reaches (and contaminates) the production well. However, a monitoring system in the production well would not be capable of making such a determination in time to prolong the production. This is because the system in the production well would only identify the injection fluid front when it has already approached the production well. Also, if one of the other injection wells' injection fluid had been misdirected away from the production well due to the permeability anisotropy around that injection well, the production well would not detect that fluid front over a length of time but would not provide any information about the directivity of that injection fluid.
Embodiments detailed herein describe a method of monitoring boundary conditions from the injection well itself. By detecting the boundary between the material injected through the injection well and surrounding material, the fluid front advancing toward a production well (or in an unintended direction other than the direction of the production well) or material injected into a storage reservoir may be effectively monitored during its travel into the reservoir and throughout the useful life of the reservoir.
While each of the various types of transmitter/receiver systems that may be used as the monitoring system 130 may have individual strengths, the exemplary transient EM monitoring system 130 addresses two concerns. First, transient (time-domain) measurements relative to continuous-wave measurements provide improved spatial resolution. Second, signal-to-noise ratio is improved by increasing the strength of the transmitter and receiver magnetic dipoles. The transmitter 110 and receiver 120 of the present embodiment are designed to generate a relatively large switchable dipole (e.g., dipole moment of 1 kAm2) with power consumption that is more than a hundred times less than with a conventional long-coil. The monitoring system 130 measures conductivity. The monitoring system 130 operates by altering the transmitted electromagnetic (EM) field to produce a transient EM signal. The receiver 120 receives a signal based on the transient EM signal transmitted by the transmitter 110. This received signal represents the conductivity of the surrounding material.
By detecting a transition in conductivity of that surrounding material, the fluid front of the injection substance 101 may be detected and its directivity and speed may be monitored. The directivity of the injection substance 101 is based on the permeability anisotropy around the injection well 100. That is, the injection substance 101 will not flow in all directions uniformly from the injection well 100 and, as noted above, may not reach a targeted production well 150 at all within a given period of time. By monitoring the flow of the injection substance 101, the permeability anisotropy around the injection well 100 may be determined. Because the exemplary monitoring system 130 (transient EM) measures conductivity, an injection substance 101 that has a lower conductivity than that of surrounding material (e.g., oil around a production well 150) may be monitored for a longer distance away from the injection well 100 than an injection substance 101 with a higher conductivity than that of surrounding material. For example, CO2 has a lower conductivity than oil. Thus, when CO2 is the injection substance 101 injected into the injection well 100, it may be monitored as it advances toward the oil for a greater distance than if water (with a higher conductivity than oil) were used as the injection substance 101.
While one or more embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.
Claims
1. A method of monitoring an injection substance injected into an injection well penetrating the earth, the method comprising:
- disposing a monitoring system in a borehole, both a transmitting and a first receiving portion of the monitoring system being disposed in the borehole;
- injecting the injection substance into the injection well; and
- monitoring, using a processor processing the received signal, flow of the injection substance out of the injection well.
2. The method according to claim 1, wherein the disposing the monitoring system in the borehole is in the injection well.
3. The method according to claim 2, further comprising disposing a second receiving portion of the monitoring system including one or more receivers in the injection well.
4. The method according to claim 2, further comprising disposing a second receiving portion of the monitoring system including one or more receivers in a monitor well proximate to the injection well.
5. The method according to claim 1, wherein the disposing the monitoring system in the borehole is in a monitor borehole proximate to the injection well.
6. The method according to claim 1, wherein the disposing the monitoring system in the borehole includes disposing at least one electromagnetic (EM) transmitter in the borehole, altering, using a controller coupled to the at least one EM transmitter, the transmitted EM field to produce a transient EM signal, and receiving, using one or more receivers disposed in the borehole, a received signal based on the transient EM signal.
7. The method according to claim 6, further comprising determining conductivity based on the received signal.
8. The method according to claim 7, wherein the monitoring includes identifying a boundary between the injection substance and another substance based on the conductivity.
9. The method according to claim 1, wherein the monitoring includes monitoring a direction of the flow.
10. The method according to claim 9, wherein the monitoring the direction of the flow includes determining permeability anisotropy of formation surrounding the injection well.
11. The method according to claim 1, wherein the transmitting portion and the receiving portion of the monitoring system move along a length of the borehole and the monitoring is performed at different depths.
12. The method according to claim 1, wherein a plurality of the monitoring systems are disposed along a length of the borehole.
13. The method according to claim 1, further comprising disposing a casing in the borehole and a magnetically permeable material surrounding the casing, wherein the disposing the monitoring system is between the magnetically permeable material and the borehole wall.
14. A method of monitoring an underground reservoir storing a substance introduced through an injection well, the method comprising:
- disposing a monitoring system in a borehole, both a transmitting portion and a first receiving portion of the monitoring system being disposed in the borehole;
- injecting the injection substance into the injection well for storage in the underground reservoir; and
- monitoring, using a processor processing the received signal, boundary conditions surrounding the underground reservoir.
15. The method according to claim 14, wherein the disposing the monitoring system in the borehole is disposing the monitoring system in the injection well.
16. The method according to claim 15, further comprising disposing a second receiving portion of the monitoring system including one or more receivers in the injection well.
17. The method according to claim 15, further comprising disposing a second receiving portion of the monitoring system including one or more receivers in a monitor well proximate to the injection well.
18. The method according to claim 14, wherein the disposing the monitoring system in the borehole is disposing the monitoring system in a monitor borehole proximate to the injection well.
19. The method according to claim 14, wherein the disposing the monitoring system includes disposing at least one electromagnetic (EM) transmitter in the borehole, altering, using a controller coupled to the at least one EM transmitter, the transmitted EM field to produce a transient EM signal, and receiving, using one or more receivers disposed in the borehole, a received signal based on the transient EM signal.
20. The method according to claim 14, further comprising determining conductivity based on the received signal, wherein the monitoring includes identifying a boundary between the substance and another substance surrounding the underground reservoir based on the conductivity.
21. The method according to claim 14, wherein the monitoring includes detecting a leak in a seal of the underground reservoir based on a flow of the substance out of the underground reservoir.
22. The method according to claim 14, wherein the transmitting portion and the receiving portion of the monitoring system move along a length of the borehole and the monitoring is performed at different depths.
23. The method according to claim 14, wherein a plurality of the monitoring systems are disposed along a length of the borehole.
24. The method according to claim 14, further comprising disposing a casing in the borehole and a magnetically permeable material surrounding the casing, wherein the disposing the monitoring system is between the magnetically permeable material and the borehole wall.
25. A method of monitoring an injection substance injected into an injection well penetrating the earth, the method comprising:
- disposing a transmitting portion of a monitoring system in a first borehole;
- disposing a receiving portion of the monitoring system in a second borehole;
- synchronizing the transmitting portion and the receiving portion time;
- injecting the injection substance into the injection well; and
- monitoring, using a processor processing the received signal, flow of the injection substance out of the injection well.
Type: Application
Filed: Oct 17, 2013
Publication Date: Jul 3, 2014
Applicant: BAKER HUGHES INCORPORATED (Houston, TX)
Inventors: Sushant M. Dutta (Houston, TX), Daniel T. Georgi (Houston, TX), Randy Gold (Houston, TX), Arcady Reiderman (Houston, TX)
Application Number: 14/056,239
International Classification: E21B 44/00 (20060101);