Fracturing operations are conducted in a well to improve the flow of production fluid from a surrounding formation into a wellbore. A variety of fracturing techniques can be employed and involve pumping a fracturing fluid downhole and into the surrounding formation to ultimately improve the flow of production fluids through the formation and into the wellbore. If sand control is required, a separate sand control completion is deployed in the wellbore in an additional procedure to facilitate removal of particulates from produced fluid.
In general, the present invention provides a multi-stage well treatment system having a plurality of packers and a plurality of flow valves. The multi-stage well treatment system can be moved downhole in a wellbore and actuated to isolate a plurality of sections along the wellbore for treatment. The system and methodology enable treatment, e.g. fracturing, of select sections via the flow valves. However, the flow valves also are used to establish a permeable, stabilized pack surrounding each flow valve in the annulus of each section.
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 generally relates to a system and method for facilitating well treatments, e.g. fracturing treatments, and for placing permeable, stabilized packs at a plurality of isolated sections along the wellbore. Generally, a multi-stage well system is run into a wellbore and actuated to isolate a plurality of sections along the wellbore. The multi-stage well system comprises flow valves arranged so that at least one flow valve is in each isolated section. The flow valves are used to inject treatment fluid, e.g. fracturing fluid, into each of the sections. However, the flow valves also can be used to direct a proppant into the annulus at each section. The proppant is used to form a stabilized filter pack in each section which functions as a sand control tool.
The multi-stage well system uses a series of isolation devices, e.g. packers, deployed along a tubular structure to form a wellbore completion able to isolate the wellbore sections. The packers can be used in either cased hole or open hole completions to divide the well into manageable sections. These manageable sections enable stimulation, and later production, that is specific to intervals bounded by pairs of packers. The flow valves enable well treatments, e.g. fracturing treatments, and also facilitate creation of the permeable, stabilized packs in the isolated wellbore sections. Generally, each wellbore section has a flow valve positioned along the tubular structure towards the top of the section so that flow through the isolation valve is generally at the upper end of each isolated section when the well system is actuated in a wellbore. During production, production fluids flow from the surrounding formation and through the stabilized pack before entering the completion through the flow valve in each isolated wellbore section.
The multi-stage well system can be used to carry out a variety of well treatment procedures in many types of wells, including vertical wells and deviated wells, e.g. horizontal wells. The well system also can be utilized in many types of well environments, including high-temperature environments, high-pressure environments, H2S environments, and CO2 environments. The treatment and production operations can be carried out in sandstone, carbonate, shale, coal or other types of formations.
Referring generally to
In the embodiment illustrated, multi-stage treatment system 24 is formed as part of a single tubing string/completion 30 deployed in wellbore 22 via a conveyance 32, such as tubing. In the example provided, well system 20 is deployed into a generally vertical well extending down from a surface rig 36 or other deployment equipment positioned at a surface location 38. However, well system 20 also can be deployed into deviated wellbores, such as horizontal wellbores.
Multi-stage treatment system 24 comprises a plurality of isolation devices 40, e.g. packers, which can be actuated to isolate sections 42 along wellbore 22. The multi-stage treatment system 24 further comprises a plurality of flow valves 44 with at least one flow valve 44 disposed in each section 42 between adjacent packers 40. Generally, the flow valve 44 in each wellbore section 42 is positioned in the upper portion of the section 42 between adjacent packers 40. The flow valves 44 can be used to direct/inject treatment fluid into each isolated well section 42 during a treatment procedure. For example, flow valves 44 can be used to direct a fracturing fluid into the surrounding formation 26 at each well section 42 to fracture the desired formation zones, thereby promoting the flow of production fluids to wellbore 22. In many applications, the treatment procedure is conducted at individual well sections 42 and progresses from one well section 42 to the next. In a specific application, the multi-stage treatment system 24 is used to conduct a well stimulation procedure by placing the flow valves 44 between external packers 40 at multiple well sections 42. The packers 40 function to divide the well into manageable sections that enable stimulation and production specific to the interval bounded by packers at each end of that interval/well section. Examples of stimulation procedures include matrix stimulation, acid fracturing stimulation, and propped fracturing stimulation.
Upon completion of the treatment procedure, production fluid can be flowed from the various regions of formation 26 into completion 30 via flow valves 44. As described in greater detail below, the inflow of production fluid is filtered by a stabilized filter pack disposed in the wellbore annulus surrounding completion 30 at each wellbore section 42 formed between adjacent packers 40. In the embodiment illustrated, packers 40 and flow valves 44 are mounted on a tubular structure 46. The tubular structure 46 can be used to conduct treatment fluids to flow valve 44 and also to receive production fluids, e.g. oil, through the flow valves 44.
In
Referring to
In the example illustrated in
Accordingly, multi-stage well system 24 can be used for well treatment, e.g. delivery of acid or fracturing fluid, and also for sand control. Certain treatment procedures can be combined or sequential. The well system 24 further provides a quick method to place multizone, permeable, stabilized packs that also have the ability to be easily isolated in the future if an undesirable production profile develops. For example, select wellbore sections 42 can be isolated simply by closing the appropriate flow valve 44.
Once well system 20 is deployed in wellbore 22, the permeable, stabilized packs 56 can be formed in some or all of the annular regions 54. The stabilized packs 56 can be formed in an open hole or a cased hole. In the embodiment illustrated in
The well system 20 can be used in a variety of well treatment and production applications. In one application example, the treatment string/completion 30 is initially deployed in wellbore 22, as illustrated by block 66 in the flowchart of
After completing the desired well treatment and the deposition of permeable, stabilized packs 56, a desired formation fluid can be flowed into wellbore 22 and into tubing string 30 through stabilized packs 56, as illustrated by block 74. The stabilized packs 56 filter the inflowing fluid, thus removing particulates from the fluid. After flowing through stabilized packs 56, the formation fluid moves into completion 30 through the appropriate flow valve or flow valves 44 in each isolated section 42. Over time, if one or more of the isolated sections 42 begin producing in an undesirable manner, flow through that particular stabilized pack 56 and isolated section 42 can be reduced or blocked. For example, the flow valve 44 in each isolated section 42 can be used to restrict or close off flow through that section as desired to improve overall production, as illustrated by block 76. Undesirable production in one or more of the well sections 42 may result from the production of gas, water or other undesirable fluids at some point during the life of the well.
Depending on the environment and the completions used to produce fluids from formation 30, the procedures for stimulation/treatment and production can be adjusted. In
Once the wellbore is prepared, perforations 66 are formed in each of the well sections 42, as illustrated by block 80. The perforations 66 also can result from re-perforation by forming, for example, oriented gravel pack perforations into the plane of fracture. Subsequently, additional preparatory procedures may be conducted to prepare the wellbore for receipt of well system 20, as illustrated by block 82. For example, when well sections are thin or open hole completions are utilized, an optional procedure may be employed to squeeze well intervals with resin to consolidate the formation. Pressure tests are then performed on the intervals subjected to resin consolidation.
Following any additional preparatory procedures, the multi-stage well system 20 is run in hole, as illustrated by block 84, and the packers 40 are set to isolate well sections 42. A treatment procedure can then be performed in each isolated well section 42, as illustrated by block 86. By way of example, the treatment procedure may comprise sequentially performing an acidizing or fracturing procedure at each of the isolated well zones 42. The well sections 42 are then filled with, for example, resin coated sand to establish the permeable, stabilized packs 56, as illustrated by block 88. The resin coated sand is allowed to reach a required minimum strength, and a final well clean out can be conducted, as illustrated by block 90.
A final completion is then run downhole, as illustrated by block 92. The final completion may comprise a variety of production related completions, including completions designed for artificially lifting production fluids to a desired collection location. For example, an electric submersible pumping system can be delivered downhole to pump the fluids that collect within the well system 20. With the final completion in place, the well can be placed on production to deliver production fluids to the desired collection location, as illustrated by block 94. During production, the flow valves 44 can be used to reduce or stop fluid flow through well sections 42 that experience undesirable water cut or gas influx.
As described above, well system 20 can be constructed in a variety of configurations for use in many environments and applications. Additionally, the size and arrangement of the components can be adjusted according to the environment and according to treatment or production parameters. A variety of packers or other isolation devices can be used in both open hole and cased hole applications. Also, various types of flow valves 44 can be used to direct proppant and various treatment fluids outwardly or to conduct the inward flow of production fluids. Furthermore, the permeable, stabilized packs 56 can be formed with a variety of proppants, additives and materials capable of readily forming multiple permeable, stabilized packs.
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.