Wells – Processes – Providing porous mass of adhered filter material in well
Reexamination Certificate
2000-12-13
2002-08-27
Suchfield, George (Department: 3672)
Wells
Processes
Providing porous mass of adhered filter material in well
C166S280100, C166S281000, C166S295000, C507S219000, C507S924000, C428S405000, C428S407000, C523S131000
Reexamination Certificate
active
06439309
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to silyl-modified polyamide compositions. This invention also relates generally to subterranean formation treatments and, more specifically, to subterranean formation treatments employing silyl-modified polyamides to minimize migration or movement of naturally occurring or introducable solid particulates within a subterranean formation, and/or a wellbore penetrating a subterranean formation.
2. Description of the Related Art
Production of particulate solids with subterranean formation fluids is a common problem. The source of these particulate solids may be unconsolidated material from the formation (including fines), proppant from a fracturing treatment, particulate from a sand control treatment and/or fines generated from crushed fracture proppant. Production of solid proppant material is commonly known as “proppant flowback.” In addition to causing increased wear on downhole and surface production equipment, the presence of particulate materials in production fluids may also lead to significant expense and production downtime associated with removing these materials from wellbores and/or production equipment. Accumulation of these materials in a wellbore may also restrict or even prevent fluid production. In addition, loss of proppant due to proppant flowback may also reduce conductivity of a fracture pack.
Hydraulic fracturing is a common stimulation technique used to enhance production of fluids from subterranean formations. In a typical hydraulic fracturing treatment, fracturing treatment fluid containing a solid proppant material is injected into the formation at a pressure sufficiently high enough to cause the formation or enlargement of fractures in the reservoir. During a typical fracturing treatment, proppant material is deposited in a fracture, where it remains after the treatment is completed. After deposition, the proppant material serves to hold the fracture open, in doing so enhancing the ability of fluids to migrate from the formation to the well bore through the fracture. Because fractured well productivity depends on the ability of a fracture to conduct fluids from a formation to a wellbore, fracture conductivity is an important parameter in determining the degree of success of a hydraulic fracturing treatment.
One problem related to hydraulic fracturing treatments is the creation of reservoir “fines” and associated reduction in fracture conductivity. These fines may be produced when proppant materials are subjected to reservoir closure stresses within a formation fracture which cause proppant materials to be compressed together in such a way that small particles (“fines”) are generated from the proppant material and/or reservoir matrix. In some cases, production of fines may be exacerbated during production/workover operations when a well is shut-in and then opened up. This phenomenon is known as “stress cycling” and is believed to result from increased differential pressure and closure stress that occurs during fluid production following a shut-in period. Production of fines is undesirable because of particulate production problems, and because of reduction in reservoir and/or fracture proppant pack permeability due to plugging of pore throats in the reservoir matrix and/or proppant pack. Fines composed of formation material (e.g., shale, sand, coal fines, etc.) may present similar problems and may be produced, for example, within a hydraulically fractured formation due to stresses and forces applied to the formation during the fracture treatment.
In an effort to control or prevent production of formation or proppant materials, many methods have been developed. Included among these are those methods commonly referred to as gravel packing and frac packs. These methods commonly employ particulate materials that are placed downhole with a gelled carrier fluid (e.g., aqueous-based fluid such as gelled brine). For example, a gravel pack operation may be carried out on a wellbore that penetrates a subterranean formation to address the production of formation particles into the wellbore from the formation during production of formation fluids. In such a method, a screen assembly may be placed within the wellbore adjacent the subterranean formation. Particulate material may be introduced with a carrier fluid into the wellbore and placed adjacent the subterranean formation by circulation so as to form a fluid-permeable pack in an annular area between the exterior of the screen and the interior of the wellbore that serves to reduce or substantially prevent the passage of formation particles from the subterranean formation into the wellbore during production of fluids from the formation, while at the same time allowing passage of formation fluids from the subterranean formation through the screen into the wellbore.
In another gravel pack method, particulate material may be introduced into a wellbore and placed opposite a formation (open hole, perforations, etc.) in the absence of a screen, and then consolidated with a curable resin (e.g., present as a self-curing coating on the particles, a curable coating on the particles that is cured with a separately introduced binding agent, etc.) or other suitable material to form a permeable consolidated mass. A core of the consolidated permeable mass may then be drilled out, leaving an annular sheath or pack of consolidated and permeable material to reduce or substantially prevent the passage of formation particles from the subterranean formation into the wellbore during production of fluids from the formation, while at the same time allowing passage of formation fluids from the subterranean formation through the screen into the wellbore, in a manner similar to that described for the gravel pack with screen. In some cases, consolidatable particulate materials may alternatively be employed in conjunction with gravel pack screens, in a manner similar to that previously described. In either case, conventional curable resins typically employed for consolidation purposes (e.g., epoxide resins) are often responsible for reduction in permeability or conductivity of the formation and/or sand control particulate pack.
In other examples, fracturing methods utilizing special types of proppants and/or additives to proppants have been employed to help form a fracture pack in the reservoir which is resistant to proppant flowback. One method of this type utilizes resin-coated proppant materials designed to help form a consolidated and permeable fracture pack when placed in the formation. Among the ways this method may be carried out are by mixing a proppant particulate material with an epoxy resin system designed to harden once the material is placed in the formation, or by the use of a pre-coated proppant material which is pumped into the formation with the fracturing fluid and then consolidated with a curing solution pumped after the proppant material is in place. Although resin-coated proppant techniques may reduce proppant flowback, they may also suffer from various problems, including incompatibility of resins with cross-linker and breaker additives in the fracturing fluid, and long post-treatment shut-in times which may be economically undesirable. Resin-coated proppants may also be difficult to place uniformly within a fracture and may adversely affect fracture conductivity. In addition, if desired, resin-coated proppants may only be added to the final stages of fracturing treatments due to their expense, resulting in a fracture pack that is consolidated only in a region near the well bore.
Recently, techniques employing a mixture of solid proppant materials designed to achieve proppant flowback control have been developed. In one technique, rod-like fibrous materials are mixed with proppant material for the purpose of causing particle bridging within a fracture proppant pack so as to inhibit particle migration and proppant flowback. This technique is believed to control proppant flowback by forming a “mat” of fibers across openings in the pack which tends
Dawson Jeffrey C.
Matherly Ronald M.
Rickards Allan R.
BJ Services Company
O'Keefe Egan & Peterman, LLP
Suchfield George
LandOfFree
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