In many well environments and applications, the development of scale can be problematic for downhole completion equipment and other downhole components. Scale can result from a variety of deposits that form along the interior of tubulars, e.g. production tubing or casing, or on other well related equipment. Scale often is formed in oil or gas wells that produce water or as result of water injection to enhance recovery. If left untreated, the scale can inhibit or prevent fluid flow along the wellbore.
Several techniques have been used in the removal of scale from tubing and other well equipment. For example, some types of scale can be dissolved by a pumping specific treatment fluids downhole. In other applications, scale is removed by directing a jet of abrasive slurry against the scale to effectively chip away at the scale deposits. In any of these approaches, difficulty arises in determining the extent of the scale removal and thus the success of the treatment.
In general, the present invention provides a system and method for cleaning scale from a well and for monitoring removal of the scale. A scale removal tool and a radiation detector are deployed simultaneously into a wellbore having scale with a radioactive nature. The scale removal tool is operated to remove scale from a well component, e.g. from the interior of a tubular member. The radiation detector is utilized in locating scale deposits, measuring the extent of the scale removal, and outputting data related to the extent of scale removal.
Certain embodiments of the invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and:
In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.
The present invention relates to a system and methodology for determining the location of scale deposits and for monitoring removal of the scale. The system and methodology enable the accurate monitoring of scale removal through detection of the radioactive nature of the scale. For example, barium sulfate has a radioactive nature/signature that is detected and monitored to determine the amount of scale remaining in a well component. A radiation detector, such as a gamma ray detector, is used to detect the radiation and output data to a surface acquisition unit indicative of the amount of remaining scale.
In one example, data from the gamma ray detector is provided along with a casing collar locator log to determine the presence and location of barium sulfate scale. Gamma ray readings indicate the presence of barium sulfate scale, and higher readings indicate greater buildup of scale. A surface readout may be used to provide operational information related to the cleanout procedure, and may include a variety of parameters such as string weight, speed, pump rate, and pressure. These parameters inform an operator as to whether further cleanout progress remains feasible.
The system also can be designed to provide downhole data to the surface in real time. By way of example, data from the radiation detector and other downhole sensors can be transmitted uphole via a communication line, such as a fiber optic line. Both data from the radiation detector and data from other downhole sensors, e.g. pressure sensors, temperature sensors, casing collar locator detectors, can be sent uphole to a surface acquisition unit to enable monitoring and/or optimization of the scale removal.
Removal of scale can be accomplished by pumping appropriate scale removal materials downhole. If the cleanout equipment is conveyed downhole by coiled tubing, fluid based scale removal materials can be pumped down through the coiled tubing. In one example, scale removal material is pumped under pressure through a jetting tool used to direct high-pressure fluid through one or more jetting nozzles and against the scale buildup. The scale removal material may comprise combinations of liquid and particulate matter able to remove scale buildup when directed against the scale under pressure. For example, scale removal materials are available from Schlumberger Corporation, of Houston, Tex., and include materials containing sterling beads and cleanout gels or fluids designed to enhance the removal of scale. As the scale is removed, the radiation detector, e.g. gamma ray detector, is used to monitor the removal process.
Referring generally to
In the example illustrated, the scale buildup 30 is formed within a tubular member 32 through which bottom hole assembly 22 is run downhole. However, bottom hole assembly 22 can be utilized in the removal of scale deposits from other downhole components. The tubular member 32 may comprise casing, production tubing, completion tubing, or other tubular members deployed in a wellbore 34. As illustrated, wellbore 34 is lined with a wellbore casing 36, and desired regions can be isolated along tubular member 32 by locating one or more packers 36 between tubular member 32 and wellbore casing 36.
As illustrated in
The bottom hole assembly 22 is moved downhole to enable radiation detector 24 to detect the presence of scale deposits 30. Once detected, scale removal tool 26 is used to remove the scale buildup, and radiation detector 24 is used to monitor the removal. In the embodiment illustrated, scale removal tool 26 comprises a jetting tool, and radiation detector 24 comprises a gamma ray detector. A scale removal material is flowed under pressure downhole, e.g. through coiled tubing conveyance 42, as represented by arrows 48. The scale removal material is flowed through gamma ray detector 24 to jetting tool 26. Jetting tool 26 directs the pressurized scale removal material outwardly through one or more jets 50 against scale deposits 30.
In embodiments that utilize a coiled tubing conveyance 42, the bottom hole assembly 22 is conveyed downhole by a coiled tubing injection system 52, as illustrated in
Additionally, the communication line or communication lines 46 can be deployed downhole with conveyance 42. For example, communication line 46 can be mounted on the coiled tubing or deployed within the coiled tubing. The communication line 46 is connected to surface acquisition unit 44 to receive data sent uphole from bottom hole assembly 22. In the example illustrated, surface acquisition unit 44 may comprise a computer based control having a computer 64 with a suitable processor or processors programmed to process data received from components of bottom hole assembly 22. Computer 64 also can be used to process data received from a variety of other sensors/components of well system 20. Information on scale removal, pressure, temperature, casing collar locations, and other data can be displayed on one or more displays 66 located at the well site or at other locations. In this example, each display 66 uses a suitable graphical user interface to provide scale removal information and other desired information in a format useful to an operator. In some applications, computer 64 also can be used to output data downhole to control various downhole components.
Referring generally to
As illustrated, the scale removal tool 26 is a jetting tool located at a lower position of bottom hole assembly 22. The jetting tool 26 directs and discharges scale removal material through jetting nozzle 50, as represented by arrows 68. A filter 70 is positioned to filter the scale removal material before it enters jetting tool 26. Filter 70 is designed to remove debris that can potentially clog or damage jetting tool 26. A check valve section 72, having check valves 74, provides a well control pressure barrier. Check valve section 72 may be located adjacent filter 70 on a side opposite jetting tool 26.
The illustrated bottom hole assembly 22 also comprises a variety of sensors to detect and monitor a variety of downhole parameters. For example, radiation detector 24, e.g. a gamma ray detector, is positioned to detect radiation from the scale deposits. The radiation detector 24 comprises a flow passage 76 through which scale removal material is flowed to jetting tool 26. Other sensory devices may comprise a casing collar locator 78 and a stress detector 80 for detecting tension and compression in bottom hole assembly 22. As illustrated, casing collar locator 78 and stress detector 80 are positioned between radiation detector 24 and check valve section 72. Additionally, a monitoring section 82 may comprise one or more pressure sensors 84 and temperature sensors 86. In many applications, pressure sensors 84 are positioned to measure internal pressures within bottom hole assembly 22 and external pressures outside bottom hole assembly 22.
Data from the radiation detector 24 and other sensors, as well as control signals sent downhole from surface acquisition unit 44, are handled by an electronics section 88 that may be positioned above radiation detector 24 and monitoring section 82. Electronics section 88 is designed according to the surface acquisition system utilized. By way of example, electronics section 88 may comprise a bulkhead for terminating an optical fiber communication line, a power section to provide downhole power storage, and a suitable telemetry control for sending and receiving data. A connector 90 is used to connect bottom hole assembly 22 to coiled tubing conveyance 42 or to another type of conveyance.
The use of coiled tubing for conveying bottom hole assembly 22 downhole creates an internal flow path along which the scale removal material can be flowed downhole, while also providing a structural feature along which the communication lines 46 can be routed. As illustrated in
During a scale removal operation, data from the various sensors in bottom hole assembly 22 is provided to surface acquisition unit 44, processed as necessary to a desired form, and output to display device 66. For example, data from gamma ray detector 24 can be output to the one or more display devices 66 in a form that helps an operator identify and visualize scale build up in tubular member 32. During scale removal, the gamma ray detector 24 can be continually operated to provide updated data to surface acquisition unit 44. This allows an operator to monitor the scale removal progress. A variety of other data, including temperature data, pressure data, casing collar data and other information also can be provided to surface acquisition unit 44 and displayed for use and evaluation by an operator. Furthermore, the data can be processed by computer 64 according to a variety of models or algorithms to present additional information to an operator related to scale removal and other aspects of the well.
As the scale removal operation progresses, the gamma ray detector 24 is used to periodically or continuously measure the radioactive nature of the scale deposit. The resulting data is transmitted uphole to provide an operator with information on the extent of the remaining scale deposit. In many applications, the data can be transferred uphole in real time to keep an operator updated throughout the scale removal operation. The real time monitoring is particularly helpful in optimization of the scale removal procedure. The surface acquisition unit 44 records and displays the downhole information, allowing the operator to adjust the depth of the bottom hole assembly and to compare real time readings against an existing baseline well log to enable real time optimization of the procedure.
The present system and methodology enable monitoring of scale removal operations through detection of scale deposits based on the radiation signature of the deposits. By using a gamma ray detector, for example, the position and amount of barium sulfate scale or other radioactive scale can be determined by the strength of the radioactive signature. Also, the ability to output data to surface acquisition unit 44 in real time facilitates immediate optimization of the scale removal procedure. The scale removal is further optimized by virtue of the internal flow passage extending through the radiation detector and other bottom hole assembly components to enable pumping of a variety of treatment fluids down through a coiled tubing conveyance and through the bottom hole assembly components to the scale removal tool 26. As a result of the design and monitoring ability, both the scale removal material, e.g. treatment fluid, and the jetting tool can be selected and subsequently adjusted to optimize scale removal. In some applications, the ability to use coiled tubing as the conveyance enables and improves the functionality of a variety of communication lines, such as fiber optic lines.
Accordingly, although only a few embodiments of the present invention have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this invention. Such modifications are intended to be included within the scope of this invention as defined in the claims.