REAL TIME DOWNHOLE INTERVENTION DURING WELLBORE STIMULATION OPERATIONS
A method for completing a wellbore having a plurality of stimulation valves disposed therein at longitudinally spaced apart locations includes moving a spoolable rod into the wellbore. The rod includes a plurality of spaced apart sensors therein. At least one valve operating dart is applied to an exterior of the spoolable rod. The dart is configured to engage a selected one of the stimulation valves. A position of the at least one dart is estimated during pumping of fluid into the wellbore by measuring output of the sensors in the rod.
The invention relates generally to the field of wellbore based reservoir stimulation operations. More specifically, the invention relates to methods for wellbore intervention during reservoir stimulation through the wellbore.
BACKGROUND ARTTo increase productivity of oil and/or gas wells, hydraulic stimulation (fracturing) is typically used. One method of fracturing in wells including a plurality of depth-separated producing formations includes installation of stimulation valves, so-called “frac sleeves”, adjacent to each of the formations to be stimulated by fracturing. The fracturing is performed by pumping fluid within a string of casing or tubing installed in the wellbore. A typical well completion configuration is shown in
Each of the valves or frac sleeves wherein a plurality of such frac sleeves is used, can be opened by dropping a matching or mating ball (13 in
Because it is desirable to monitor in real time the stimulation process in the wellbore, which can be performed for example, using longitudinally distributed sensors such as temperature sensors, pressure sensors, acoustic sensors, etc., it is desirable to be able to use a device having such sensors thereon that is compatible with pumping darts or balls into the wellbore.
A method for completing a wellbore according to one aspect of the invention, where the wellbore has a plurality of stimulation valves disposed therein at longitudinally spaced apart locations, includes moving a spoolable rod into the wellbore. The rod includes a plurality of spaced apart sensors therein. At least one valve operating dart is applied to an exterior of the spoolable rod. The dart is configured to engage a selected one of the stimulation valves. A position of the at least one dart is estimated during pumping of fluid into the wellbore by measuring output of the sensors in the rod.
Other aspects and advantages of the invention will be apparent from the following description and the appended claims.
A semi stiff, spoolable rod system containing sensing fibers and/or electrical cable(s) for sensing has been developed and demonstrated by the assignee of the present invention. Such spoolable rod is used to provide services under the service mark ZIPLOG, which is a service mark of the assignee of the present invention. The system is based on pushing the spoolable rod into producing and/or fluid injection wellbores. The spoolable rod is typically disposed on a reel or winch and is pushed inside a tubing string (production tubing) inserted into the well coaxially with the wellbore casing by operating the winch. By having sensing elements, for example, optical fiber temperature and/or pressure sensing elements, at spaced apart positions incorporated into the spoolable rod, it is possible to provide real time data to the surface about well conditions during production, injection and shut-in. The foregoing spoolable rod to provide ZIPLOG services includes such sensing elements. See the Uniform Resource Locator http://www.ziebel.biz/ziplog.htm.
Referring to
The dart's or ball's 16 position along the exterior of the spoolable rod during pumping into the wellbore can be estimated during fluid pumping by measuring the amount of fluid pumped in, or by cooling of the spoolable rod 20. Cooling of the rod 20 can be estimated or monitored by measurements from distributed temperature sensors 19 in the spoolable rod 20, as well as by acoustic detection (using suitable pressure sensors incorporated into the rod 20) of the dart or ball 16 traveling into the casing 12. The fluids pumped into the casing 12 typically have a different temperature than exists at many depths within the wellbore; therefore, temperature measuring along the spoolable rod 20 will generally suffice to indicate the position of the fluids moving down into the casing 12 from the surface.
During fluid pumping operations, as explained above, distributed temperature and/or pressure sensors included in the spoolable rod (20 in
A completion system as explained above may have stimulation valves all having substantially the same interior diameter, and may include the capability of estimating progress of fluid pumped into the wellbore during pumping operations.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
Claims
1. A method for completing a wellbore having a plurality of stimulation valves disposed therein at longitudinally spaced apart locations, said method comprising the following steps:
- moving a spoolable rod into the wellbore, the rod including a plurality of spaced apart sensors therein;
- applying at least a first valve operating dart to an exterior of the spoolable rod; the at least a first dart configured to engage only a selected one of the stimulation valves; and
- moving the at least a first dart along the spoolable rod to engage a selected one of the stimulation valves.
2. The method of claim 1 further comprising determining a position of the at least a first dart during pumping of fluid into the wellbore by measuring output of the sensors in the rod.
3. The method of claim 1 wherein the sensors comprise temperature sensors.
4. The method of claim 1 further comprising causing the selected one of the stimulation valves to open by continuing movement of the dart after the dart engages the selected one of the stimulation valves.
5. The method of claim 1 further comprising applying at least a second valve operating dart to the exterior of the spoolable rod and determining a position thereof during pumping of fluid into the wellbore, the at least a second dart configured to engage only a second one of the stimulation valves.
6. The method of claim 4 wherein the first and second darts each have an exterior profile configured to engage a mating profile in a respective one of the stimulation valves.
7. The method of claim 1 further comprising removing the at least a first dart by withdrawing the spoolable rod from the wellbore.
8. The method of claim 1 further comprising removing the at least a first dart by withdrawing fluid from a subsurface reservoir through the wellbore.
Type: Application
Filed: Nov 16, 2009
Publication Date: Sep 13, 2012
Inventor: Henning Hansen (Alicante)
Application Number: 13/128,681
International Classification: E21B 34/06 (20060101);