Patent Application
20160123126
The embodiments described herein relate to a system and method that provides real time downhole pressure readings during a fracturing, or re-fracturing, procedure that may permit the optimization of the procedure.
Natural resources such as gas and oil may be recovered from subterranean formations using well-known techniques. Wellbores, both vertical and horizontal, may be drilled into a formation. After formation of the wellbore, a string of pipe, e.g., casing, may be run or cemented into the wellbore. Hydrocarbons may then be produced from the wellbore.
In an attempt to increase the production of hydrocarbons from the wellbore, the casing is often perforated and fracturing fluid is pumped into the wellbore to fracture the subterranean formation. Hydraulic fracturing of a wellbore has been used for more than 60 years to increase the flow capacity of hydrocarbons from a wellbore. Hydraulic fracturing pumps fluids into the wellbore at high pressures and pumping rates so that the rock formation of the wellbore fails and forms a fracture to increase the hydrocarbon production from the formation by providing additional pathways through which reservoir fluids being produced can flow into the wellbore. Pressures are known at the surface during the fracturing procedure, but often wellbore conditions between the surface and location being fractured may make it difficult, if not impossible, to predict the actual pressure of the fracturing fluid as it impacts the formation. Further, it may not be determined whether the hydraulic fracturing was effective until after completion of the fracturing procedure and the well begins to produce hydrocarbons from the recently fractured location.
A production zone within a wellbore may have been previously fractured, but the prior hydraulic fracturing treatment may not have adequately stimulated the formation leading to insufficient production results. Even if the formation was adequately fractured, the production zone may no longer be producing at desired levels. Over an extended period of time, the production from a previously fractured wellbore may decrease below a minimum threshold level. The wellbore may be re-fractured in an attempt to increase the hydrocarbon production. Again, the effectiveness of a re-fracturing procedure may not be known until the re-fracturing procedure has been completed. If not effective, a subsequent procedure costing time and money may need to be done. It may be beneficial to provide a system and method for the real time monitoring of fracturing and re-fracturing procedures.
The present disclosure is directed to system and method for providing real time pressure readings during a fracturing, or re-fracturing, procedure that overcomes some of the problems and disadvantages discussed above.
One embodiment is a method of fracturing a wellbore formation comprising positioning an end of a coiled tubing string adjacent a first location within a wellbore, the tubing string extending from a surface location to the first location. The method comprises pumping fluid down the wellbore to perform a fracturing procedure to fracture a wellbore formation adjacent the first location. The method comprises monitoring a pressure within the wellbore adjacent to the first location during the fracturing of the wellbore formation with at least one sensor connected to the surface via a communication line positioned within an interior of the coiled tubing string.
The method may include modifying the fracturing procedure substantially simultaneous with the fracturing procedure based on monitoring the pressure within the wellbore. Modifying the fracturing procedure may comprise changing a pressure of the fluid being pumped down the wellbore or changing a composition of the fluid being pumped down the wellbore. Changing the pressure of the fluid being pumped down the wellbore may comprise changing a pumping rate of the fluid being pumped down the wellbore. The fracturing procedure may be a re-fracturing procedure with the wellbore formation adjacent the first location having been previously hydraulically fractured.
The method may include actuating an isolation element connected to the coiled tubing below the first location prior to pumping fluid down the wellbore. Monitoring the pressure may include monitoring the pressure with a first sensor connected to an exterior of the coiled tubing string below the isolation element, monitoring the pressure with a second sensor connected to the exterior of the coiled tubing string above the isolation element, and monitoring the pressure within a third sensor connected to the interior of the coiled tubing string, wherein the first, second, and third sensors are connected to the communication line. Pumping fluid down the wellbore may comprise pumping fluid down an annulus between the exterior of the coiled tubing string and the wellbore. Pumping fluid down the wellbore may comprise pumping the fluid down the interior of the coiled tubing string. Pumping fluid down the wellbore may comprise pumping the fluid down the interior of the coiled tubing string and pumping the fluid down an annulus between the exterior of the coiled tubing string and the wellbore.
Monitoring the pressure may comprise monitoring the pressure with a first sensor connected to an exterior of the coiled tubing string and monitoring the pressure with a second sensor connected to the interior of the coiled tubing string, wherein the first and second sensors are connected to the communication line. The method may include actuating a first isolation element connect to the coiled tubing string below the first location and actuating a second isolation element connected to the coiled tubing string above the first location, the first and second isolation elements being actuated prior to pumping fluid down the wellbore. Pumping fluid down the wellbore may comprise pumping the fluid down the interior of the coiled tubing string and out a port between the first and second isolation elements. Monitoring the pressure may comprise monitoring the pressure with a first sensor connected to an exterior of the coiled tubing string below the first isolation element, monitoring the pressure with a second sensor connected to the exterior of the coiled tubing string between the first and second isolation elements, monitoring the pressure with a third sensor connected to the exterior of the coiled tubing string above the second isolation element, and monitoring the pressure with a fourth sensor connected to the interior of the coiled tubing string, wherein the first, second, third, and fourth sensor are connected to the communication line.
The method may comprise actuating an isolation element prior to pumping the fluid down the wellbore, the isolation element may be connected to the coiled tubing string and be positioned above the first location, and wherein pumping fluid down the wellbore may comprise pumping fluid down the interior of the coiled tubing string. Monitoring the pressure may comprise monitoring the pressure with a first sensor connected to an exterior of the coiled tubing string below the isolation element, monitoring the pressure with a second sensor connected to the exterior of the coiled tubing string above the isolation element, and monitoring the pressure with a third sensor connected to the interior of the coiled tubing string, wherein the first, second, and third sensors are connected to the communication line. The method may include providing diverting material within the wellbore below the first location to isolate a portion of the wellbore below the first location, wherein the diverting material is provided prior to pumping fluid down the wellbore to perform the fracturing procedure.
One embodiment is a system for fracturing a multizone wellbore comprising a coiled tubing string positioned within a multizone wellbore, the tubing string extends from a surface location with an end being positioned adjacent a first location in the multizone wellbore. The system comprising a communication line within an interior of the coiled tubing string and at least one pressure sensor connected to the communication line. The communication line may be an electrical line or a fiber optic line.
The system may comprise a first pressure sensor connected to an exterior of the coiled tubing string and a second pressure sensor connected to the interior of the coiled tubing string. The system may comprise a first isolation element connected to the coiled tubing string and a third pressure sensor connected to the exterior of the coiled tubing string, wherein the first pressure sensor is positioned below the first isolation element and the third pressure sensor is positioned above the first isolation element. The first isolation element may be positioned below a wellbore location to be fractured. The system may comprise a second isolation element connected to the coiled tubing string, a port in the coiled tubing string between the first and second isolation elements, and a fourth pressure sensor connected to the exterior of the coiled tubing string, wherein the third pressure sensor is positioned below the second isolation element and the fourth pressure sensor is positioned above the second isolation element. The communication line and the at least one pressure sensor may provide substantially real time monitoring of pressure during a fracturing procedure.
While the disclosure is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the intention is to cover all modifications, equivalents and alternatives falling within the scope of the invention as defined by the appended claims.
For illustrative purposes only,
A production zone may have as few as a single fracture cluster or may include more than ten (10) fracture clusters. The multiple zones of a multizone horizontal wellbore 1 may include a plurality of fracture clusters 10, 20, and 30 that extend into the formation 5 that surrounds the casing 6 of the multizone horizontal wellbore 1. As discussed above, the formation 5 is fractured by a plurality of fracture clusters 10, 20, and 30 to increase the production of hydrocarbons from the wellbore. When the rate of production from the horizontal wellbore decreases below a minimum threshold value it may be necessary to re-fracture selected fracture clusters 10, 20, and 30 within the wellbore 1.
A coiled tubing string 7 may be positioned within the casing 6 of the horizontal wellbore 1 having a packer or sealing element 50, hereinafter referred to as an isolation element. The isolation element 50 may be actuated to create a seal in the annulus between the coiled tubing 7 and the casing 6. The coiled tubing 7 includes an electrical or fiber optic line 15, also referred to as a communication line or e-line, within the interior of the coiled tubing 7. Although shown in a horizontal wellbore 1, the coiled tubing 7 with an electrical line 15 may also be used in a vertical wellbore as would be appreciated by one of ordinary skill in the art having the benefit of this disclosure. The e-line 15 extends from the surface to the end or near the end of the coiled tubing 7. The e-line 15 is connected to one or more pressure sensors 25 connected to the coiled tubing 7. The e-line 15 is connected to a first pressure sensor 25 connected to the exterior of the coiled tubing 7 below the isolation element 50 and a second pressure sensor 25 connected to the exterior of the coiled tubing 7 above the isolation element 50. The first and second pressure sensors 25 may be used to monitor the annulus pressure above and below isolation element 50 via the e-line 15. The e-line 15 is connected to a third pressure sensor 25 positioned to monitor the pressure within the interior of the coiled tubing 7. The location and number of the pressure sensors 25 may be varied depending on the application as detailed herein and would be appreciated by one of ordinary skill in the art having the benefit of this disclosure.
The isolation element 50 may be positioned uphole of the lowermost fracture cluster 10a and actuated to create a seal between the coiled tubing 7 and the casing 6 of the horizontal wellbore 1.
The communication line 15 is connected to a first pressure sensor 25 connected to the exterior of the coiled tubing 7 below the second isolation element 120, is connected to a second pressure sensor 25 connected to the exterior of the coiled tubing 7 between the first and second isolation elements 110 and 120, is connected to a third pressure sensor 25 connected to the exterior of the coiled tubing string above the first isolation element 110, and is connected to a fourth pressure sensor 25 connected to the interior of the coiled tubing 7. The coiled tubing is connected to a pump 8 that may be used to pump fluid down the coiled tubing 7 to fracture 12, or re-fracture, the formation 5 through perforations 2 in the casing 6. The communication line 15 may be connected to a processing device 70 used to analyze the data from each of the pressure sensors 25 connected to the communication line 15. The processing device 70 may determine how to optimize the fracturing, or re-fracturing, procedure in real time, or near real time, via the data received from the pressure sensors 25 via the communication line 15 during the fracture, or re-fracturing, procedure.
Although this invention has been described in terms of certain preferred embodiments, other embodiments that are apparent to those of ordinary skill in the art, including embodiments that do not provide all of the features and advantages set forth herein, are also within the scope of this invention. Accordingly, the scope of the present invention is defined only by reference to the appended claims and equivalents thereof.
