Patent Application
20110005752
The present invention relates to apparatus and methods for controlling the production of fluid through a device in a wellbore and methods for constructing said apparatus, and more particularly relates, in one non-limiting embodiment, to apparatus for and methods of inhibiting and controlling the flow of water through a wellbore from subterranean formations during hydrocarbon recovery operations and methods for constructing said apparatus.
Hydrocarbons such as oil and gas are recovered from a subterranean formation using a wellbore drilled into the formation. Unwanted water production is a major problem in maximizing the hydrocarbon production potential of a subterranean well. Tremendous costs may be incurred from separating and disposing of large amounts of produced water, inhibiting the corrosion of tubulars contacted by the water, replacing corroded tubular equipment downhole, and surface equipment maintenance. Shutting off, preventing and controlling unwanted water production is a necessary condition to maintaining a productive field.
Oil and gas wells are typically completed by placing a casing along the wellbore length and perforating the casing adjacent each such production zone to extract the formation fluids (such as hydrocarbons) into the wellbore. These production zones are sometimes separated or isolated from each other by installing a packer between the production zones. Fluid from each production zone entering the wellbore is drawn into a tubing that runs to the surface. It is desirable to have substantially even drainage along the production zone. Uneven drainage may result in undesirable conditions such as an invasive gas cone or water cone. In the instance of an oil-producing well, for example, a gas cone may cause an in-flow of gas into the wellbore that could significantly reduce oil production. Similarly, a water cone may cause an in-flow of water into the oil production flow that reduces the amount and quality of the produced oil.
Accordingly, it is desired to provide even drainage across a production zone and/or the ability to selectively close off or reduce in-flow within production zones experiencing an undesirable influx of water and/or gas. In other words, it would additionally be desirable to discover an apparatus and method which could improve the control of unwanted water production from subsurface formations.
There is provided in one non-limiting embodiment a wellbore device for controlling a flow of a fluid through a flow path therein. The wellbore device includes a container comprising a flow path and a consolidated water sensitive porous medium (WSPM) packed within the flow path of the wellbore device container. In turn, the WSPM includes solid particles and at least one water hydrolyzable polymer at least partially coated on the solid particles.
There is additionally provided in one non-restrictive version, a method of constructing a wellbore device for controlling a flow of a fluid through a flow path in the wellbore device, where the method involves mixing solid particles with at least one water hydrolyzable polymer in the presence of a fluid that may be water or brine to give a mixture. The method further includes at least partially drying the mixture. Additionally the method involves packing the at least partially dried mixture into the flow path of the container of the wellbore device to form a consolidated water sensitive porous medium (WSPM).
There is also provided, in another non-limiting form, a method for controlling a flow of a fluid through a flow path in a wellbore device in a wellbore. The method involves flowing the fluid through the flowpath in the wellbore device and controlling a resistance to flow of the fluid through the flow path whereby: resistance to flow increases as water content of the fluid increases, and resistance to flow decreases as water content of the fluid decreases. The wellbore device used includes a container (which may be coextensive therewith) comprising the flow path and a consolidated water sensitive porous medium (WSPM) packed within the flow path of the wellbore device container. In turn the WSPM includes solid particles and at least one water hydrolyzable polymer at least partially coated on the solid particles.
A method has been discovered for building a water sensitive porous medium (WSPM) to control downhole water production through a flowpath in a wellbore device installed inside of a wellbore. The WSPM may be constructed of water-soluble or water-hydrolyzable, high molecular weight polymers which are coated on solid particles, such as sand, glass beads, and ceramic proppants. The coated particles are packed under high pressure to form a consolidated homogenous and high porosity porous medium within a container of a wellbore device. The container and the wellbore device may be separate structures, where the container is part of the wellbore device, or the container and the wellbore device may be the same and coextensive. After the polymers are fully hydrolyzed in water or brine, the polymers may be optionally crosslinked with crosslinking agents. The solid particles may be mixed with the polymer solution, e.g. in a blender or mixer, at a particular ratio.
As a blender or mixer is continuous stirring the mixture of solid particles and polymer solution, blowing ambient air, hot air, nitrogen, or vacuuming is applied to the mixture to at least partially or completely dry the polymer. The polymer coated particles are loaded into a container to pack into consolidated porous medium at high pressure. The packed container, as part of a downhole tool, is installed in a wellbore. When formation water is flowed through the WSPM interstitial flow channels, the coated polymers extend their polymer chains into the pore flow channels, resulting in increased fluid flow resistance. Conversely, when oil flows through the WSPM, the polymer chains shrink back to open the flow channels wider for the desired oil flow. This process has been demonstrated to be repeatable and reversible as water/oil fluid composition varies.
When water mixed with oil flows through the WSPM, the magnitude in pressure drop across the flow channels depends on the percentage of water in the mixture (water/oil ratio, or WOR). Higher water cuts result in higher resulting pressure drops. As will be discussed, lab testing data has confirmed that pressure drops across WSPM change with water percentage of flowing through fluids.
More specifically, the production of unwanted subterranean formation water may be prevented, controlled or inhibited by a method involving treating particles with high molecular weight, water-hydrolyzable polymers, and incorporating the particles into a water sensitive porous medium (WSPM) in a wellbore device placed within the wellbore. The polymer-coated particles are introduced into a container of a wellbore device under high pressure to form a consolidated WSPM in the device before its introduction downhole.
Generally, the relatively high molecular weight polymers that have components or functional groups that anchor, affiliate or attach onto the surface of the solid particles. The polymers are hydrophilic and/or hydrolyzable meaning they swell or expand in physical size upon contact with water. The average particle size of the particles may range from about 10 mesh to about 100 mesh (from about 2000 microns to about 150 microns). Alternatively, the average particle size of the particles may range from about 20 mesh independently to about 60 mesh (from about 840 microns to about 250 microns); where the term “independently” means that any lower threshold may be combined with any upper threshold. Thus, it should be understood that the solid particles which serve as a substrate to the water hydrolyzable polymer are relatively small, particulate matter, but should not be confused with atomic particles or subatomic particles.
The particles may be any of a wide variety of solid particulate material; suitable materials include, but are not necessarily limited to, sand, glass beads, ceramic beads, metal beads, bauxite grains, walnut shell fragments, aluminum pellets, nylon pellets and combinations thereof, including conventional proppants and gravel, and, including proppants and gravel of to-be-developed materials. Proppants are known in the oilfield as sized particles typically mixed with fracturing fluids to hold open fractures after a hydraulic fracturing treatment. Proppants are sorted for size and sphericity to provide an effective conduit for the production of oil and/or gas from the reservoir to the wellbore. “Gravel” has a particular meaning in the oilfield relating to particles of a specific size or specific size range which are placed between a screen that is positioned in the wellbore and the surrounding annulus. The size of the gravel is selected to prevent the passage of sand from the formation through the gravel pack.
Further, the solid particles, e.g. proppants or gravel, may suitably be a variety of materials including, but not necessarily limited to, sand (the most common component of which is silica, i.e. silicon dioxide, SiO2), glass beads, ceramic beads, metal beads, bauxite grains, walnut shell fragments, aluminum pellets, nylon pellets and combinations thereof.
The particles may be coated by a method that involves at least partially hydrolyzing the polymer in a liquid including, but not necessarily limited to, water, brine, glycol, ethanol and mixtures thereof. The particles are then intimately mixed or contacted with the liquid containing the polymer to contact the surfaces of the particles with the polymer. The liquid is then at least partially vaporized or evaporated through vacuum, or the use of heat and/or contact with a dry gas such as air, nitrogen, or the like. The coating method may be conducted at a temperature between ambient up to about 200° F. (about 93° C.), to facilitate quick drying of the coating. It may not be necessary in some embodiments to completely dry the coating.
The loading of the polymers may be a ratio of weight of solid particles to weight of dry water hydrolyzable polymer ranging from about 10,000:1 to about 10:1; alternatively ranging from about 500:1 independently to about 25:1. The solid particles should be at least partially coated by the polymer; that is, while it is desirable to completely coat the solid particles with the polymer, the method and apparatus may still be considered successful if the particles are at least partially coated to the extent the WSPM functions effectively for the purposes noted herein.
The high pressure used to pack the water hydrolyzable polymer coated particles into the container of the wellbore device through which the flow path exists may range from about 50 to about 2000 psi (about 0.3 to about 13.8 MPa), alternatively from about 100 independently to about 1000 psi (about 0.7 to about 6.9 MPa).
The WSPM placed in the wellbore will control unwanted formation water flowing through the wellbore while not adversely affecting the flow of oil and gas. When water flows into the WSPM, the polymers anchored on the solid particles expand to reduce the water flow channel and increase the resistance to water flow. The polymers may be understood to interact chemically, ionically or mechanically with a component of the produced or in-flowing formation fluids, e.g. water molecules. This desired response may be variously described as resistance, permeability, impedance, etc., where the flow of hydrocarbons (e.g. oil and gas) is desirable, but the flow of water is not. This interaction varies the resistance to flow across the flow path of the wellbore device. When oil and/or gas flow through this special porous media, the polymers shrink to open the flow channel for oil and/or gas flow. The pre-treated particles, (e.g. proppants) are expected to form homogeneous porous media with the polymer uniformly distributed in the media to increase the efficiency of the polymer controlling unwanted water production.
In more detail, suitable water hydrolyzable polymers include those having a weight average molecular weight greater than 100,000. Suitable, more specific examples of water hydrolyzable polymers include, but are not necessarily limited to, homopolymers and copolymers of acrylamide, sulfonated or quaternized homopolymers and copolymers of acrylamide, polyvinylalcohols, polysiloxanes, hydrophilic natural gum polymers and chemically modified derivatives thereof. Crosslinked versions of these polymers may also be suitable, including but not necessarily limited to, crosslinked homopolymers and copolymers of acrylamide, crosslinked sulfonated or quaternized homopolymers and copolymers of acrylamide, crosslinked polyvinylalcohols, crosslinked polysiloxanes, crosslinked hydrophilic natural gum polymers and chemically modified derivatives thereof. Further specific examples of suitable water hydrolyzable polymers include, but are not necessarily limited to, copolymers having a hydrophilic monomeric unit, where the hydrophilic monomeric unit is selected from the group consisting of ammonium and alkali metal salt of acrylamidomethylpropanesulfonic acid (AMPS), a first anchoring monomeric unit based on N-vinylformamide and a filler monomeric unit, where the filler monomeric unit is selected from the group consisting of acrylamide and methylacrylamide. Additional suitable water hydrolyzable polymers include, but are not necessarily limited to, copolymers of vinylamide monomers and monomers containing ammonium or quaternary ammonium moieties, copolymers of vinylamide monomers and monomers comprising vinylcarboxylic acid monomers and/or vinylsulfonic acid monomers, and salts thereof, and these aforementioned copolymers further comprising a crosslinking monomer selected from the group consisting of bis-acrylamide, diallylamine, N,N-diallylacrylamide, divinyloxyethane, divinyldimethylsilane.
In an optional embodiment, when the polymers are fully or essentially completely hydrolyzed, they may be cross-linked to increase their molecular weight. Suitable crosslinking agents include, but are not necessarily limited to, aluminum, boron, chromium, zirconium, titanium, and other inorganic based and organic based crosslinking agents and other conventional crosslinking agents.
These polymers are sometimes referred to as relative permeability modifiers (RPMs) and more information about RPMs suitable to be of use in the method and compositions described herein may be found in U.S. Pat. Nos. 5,735,349; 6,228,812; 7,008,908; 7,207,386 and 7,398,825, all of which are incorporated by reference herein in their entirety.
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The invention will now be illustrated with respect to certain examples which are not intended to limit the invention in any way but simply to further illustrated it in certain specific embodiments.
One non-limiting packing procedure for building a WSPM as a water sensitive flow channel (WSFC) is set out in Table I. The procedure involves packing polymer coated proppants into 1 inch (2.5 cm) ID and 12 inch (30 cm) long stainless steel tube with both end caps forming a uniform porous medium.
In the foregoing specification, the invention has been described with reference to specific embodiments thereof, and has been demonstrated as effective in providing methods for inhibiting and controlling water flow through wellbores, particularly wellbore devices having flow paths containing solid particles coated with a water hydrolyzable polymer. However, it will be evident that various modifications and changes can be made thereto without departing from the broader spirit or scope of the invention as set forth in the appended claims. Accordingly, the specification is to be regarded in an illustrative rather than a restrictive sense. For example, specific combinations of solid particles, water hydrolyzable polymers, wellbore devices and other components falling within the claimed parameters, but not specifically identified or tried in a particular composition or method, are expected to be within the scope of this invention. Further, it is expected that the components and proportions of the solid particles and polymers and steps of constructing the wellbore devices may change somewhat from wellbore device to another and still accomplish the stated purposes and goals of the methods described herein. For example, the assembly methods may use different pressures and additional or different steps than those exemplified herein.
The words “comprising” and “comprises” as used throughout the claims is interpreted “including but not limited to”.
The present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. For instance, a wellbore device for controlling a flow of a fluid through a flow path may consist of or consist essentially of a container comprising a flow path and a consolidated water sensitive porous medium (WSPM) packed within the flow path of the wellbore device container, where the WSPM consists of or consists essentially of solid particles and at least one water hydrolyzable polymer at least partially coated on the solid particles.
This application is a continuation-in-part application of U.S. patent application Ser. No. 12/191,921 filed Aug. 14, 2008 and is also a continuation-in-part application of U.S. patent application Ser. No. 12/606,464 filed Oct. 27, 2009.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12191921 | Aug 2008 | US |
| Child | 12835023 | US | |
| Parent | 12606464 | Oct 2009 | US |
| Child | 12191921 | US |
