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  Drilling method for maintaining productivity while eliminating perforating and gravel packingRelated Patent Categories: Wells, Processes, Providing Porous Mass Of Adhered Filter Material In WellThe Patent Description & Claims data below is from USPTO Patent Application 20060108114. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention relates to a method of drilling and completing a well. [0003] More particularly, this invention relates to a method for placing a means of communication between a productive formation and a well borehole without perforating and gravel packing the well borehole at sites of production. The method also relates to minimizing formation damage caused by conventional drilling, perforating, and gravel packing. The method combines and integrates elements of well drilling and construction with the well completion in a manner to reduce time, improve safety, and maximize productivity. [0004] 2. Description of the Related Art [0005] The search for oil and gas reserves has taken the industry to remote sites including land, traditional offshore locations, and offshore deepwater. Historically the cost for exploring and developing hydrocarbons has been very high, and as the search for hydrocarbons continues in more remote areas costs are escalating because of the amount of equipment and personnel required in these areas. Because of the escalating cost it is important, that formation damage be minimized. Formation damage can negatively affect productivity of the resulting wells. Productivity needs to be as high as possible in order to ensure profitability. Also, it is important to seek ways to reduce the time spent on well construction and completion operations to minimize cost and if the number of personnel and the amount of equipment can be reduced safety inherently improves. [0006] Many hydrocarbon reservoirs are by their very nature unconsolidated rock and/or sandstone. These unconsolidated formations may produce sand particles and other debris which can cause well bore and surface facility problems as well as negatively affecting the productivity of the well. Therefore, means of preventing sand production have been developed throughout the years. [0007] One common method of well construction and completion is to drill a borehole with conventional drilling fluids, run casing into the borehole and cement the casing in place, displace the conventional drilling fluids with a clear brine, filter the brine and clean the borehole, run perforating guns in the well and perforate the casing, remove the perforating guns and re-clean the casing, re-filter to the clear brine fluids, run in the well with a gravel pack screen assembly, use high-pressure pumps place gravel pack sand between the gravel pack screen assembly into the perforation tunnels and against the formation face. This is a costly, time-consuming process. [0008] There are many disadvantages from the above procedure. These disadvantages can be broken into two categories; equipment and process reliability, and formation damage mitigation or removal. Fluid losses of the filtered brine can occur after perforating necessitating the need for a means of fluid loss control which generally entails pumping high viscosity polymer gel into the formation. There have been instances where leaks have caused perforating guns to low order detonate resulting in no or poor perforating performance and expensive fishing operations to remove the damaged perforating gun bodies. Also, gravel pack screens have failed during the high-pressure pumping operation causing additional fishing operations or worse the damage isn't discover until the well is placed on production necessitating a workover of the well. [0009] Formation damage is also a problem during conventional well construction and completion. Conventional drilling fluids can allow filtrate and solid particles to invade the formation causing restrictions in the productive pore spaces. Another source of formation damage is the shaped charges or explosives used in perforating. The energy from these explosives pushes the casing, cement, and formation aside when creating the perforation tunnel. This causes crushing of the formation matrix reducing the permeability and flow potential of the formation. Additional damage can come from the polymer gels used for controlling fluid losses after formation perforation. One method currently used to over come formation damage is hydraulic fracturing or frac packing. Frac packing is an attempt to use high-pressure pumping and hydraulic horse power to frac beyond any damage. Another method for formation damage mitigation uses acid stimulation to try and remove or dissolve formation damage caused by polymer gels or mud particle invasion. However, most mud weighting materials are solid mineral particles such as barite and bentonite that cannot be readily dissolved. [0010] The gravel pack assembly itself can serve as the restriction in the well borehole. This may cause unnecessary pressure drops which restrict production. Also, the gravel pack assembly may need to be removed for remedial operations. The process of removing an object from a well borehole is called fishing. These operations are costly and time consuming and not always successful resulting in a need to re-drill a portion of, or possibly the entire well. [0011] Another common method of well construction and completion is to drill a borehole and not run casing across the productive formation. This type of well construction is termed barefoot or openhole. Openhole completions are generally utilized after horizontal well construction. The most common practice is to run a screen assembly in the openhole section and not gravel pack on the outside of the screen between the screen and the formation. However, there has been an increasing number of openhole horizontal gravel packs performed. Formation damage is mitigated by the use of special drilling fluids termed "Drill-In-Fluids." A common problem with this type of completion is the inability to isolate areas in the completion that produce water. Water production can increase to a point that limits hydrocarbon production rates. Isolating and stopping areas of water production is made extremely difficult due to not having cemented casing in-place to help control the flow of water in the annulus between the screen and the formation. Also, the screens run in the horizontal openhole generally contain a sand control filter media. The horizontal openhole section can act as a gravity separator during production. Because the unconsolidated formation material is not kept in place with gravel pack sand in the annulus between the screen and formation, it is free to move during production. The produced fluids having a certain velocity will carry smaller formation particles more easily and at a higher velocity than the larger formation particles. Because the filter media is usually designed on the midrange particle size based on the overall particle size distribution of the formation, the smaller formation particles tend to plug the screen's sand control filter media instead of bridging on the surface of the filter media with the larger formation particles. This plugging restricts the production potential of the well and may cause a workover or loss of hydrocarbon recovery from the reservoir. [0012] Attempts to introduce devices which eliminate perforating and gravel packing are not new and have been disclosed in the past. Zandmer in U.S. Pat. No. 3,347,317 disclosed an extendable duct with solid particles acting as a gravel pack medium. Johnson disclosed an extendable device in PCT application publication number WO9626350. These devices have not been widely used. These devices trap drilling mud filter cake between the sand control filter media and formation face which limit productivity due to plugging of the formation and filter media The drilling fluids used in the well construction process generally contain minerals such as barite, bentonite, and/or clays in the form of solid particles. These particles form a filter cake on the formation face as the well is drilled. These filter cakes have a leak off rate which allows filtrate and smaller particles to enter the pore spaces of the formation and can cause considerable damage to a formation's productivity. The same filter cake can plug the sand control filter media utilized in the devices described above. In another invention disclosed by Reinhardt in U.S. Pat. No. 5,425,424, no gravel pack median is used in these extendable ducts. However, productivity is maximized by performing a hydraulic fracture treatment after extending the perforation ducts. Hydraulic fracturing is a method of bypassing formation damage and/or improving conductivity between the productive formation and the well borehole. [0013] Therefore, there is a need for a method of well construction and completion that minimizes formation damage, maximizes well productivity, and provides a means of formation isolation. Further, there is a need for a method that minimizes time spent during well completion and that improves process reliability and safety. For cased and cemented wells, there is a further need to integrate well construction and completion processes eliminating well perforation and gravel packing operations, while maximizing formation productivity. The present invention answers these needs in a cross disciplined integration of well construction (drilling) and completion processes to maximize formation productivity. SUMMARY OF THE INVENTION [0014] The present invention provides a method for drilling and completing a well, where the method achieves improved formation productivity without the need for well perforation and gravel packing. [0015] The present invention provides a method of well construction and completion including the steps of drilling an interval of a well into or into and through a productive formation in the presence of a fluid system adapted to control fluid loss, to be substantially non-damaging to the productive formation, and to form a filter cake having substantial flow back properties minimizing adverse affects on formation productivity. After the productive interval is drilled, a casing string including at least one and preferably a plurality of laterally extendable members having a sand control medium associated therewith is run into the well so that the members can be deployed to contact sites in the productive interval, i.e., the extendable members are positioned and aligned within the productive formation interval of the well. After the casing has been properly run into the well, the members are extended such that each member comes into contact with the filter cake and/or the productive formation at their associated sites, where the contacting in sufficient to allow productive formation fluids to flow through the member into the casing and out of the well. Once the members are deployed forming production conduits between an interior of the casing and the formation, the casing is cemented in place. After casing cementing, production tubing/equipment is run into the well borehole and the well is placed on production. [0016] The present invention provides a method of well construction and completion including the steps of drilling an interval of a well into or into and through a productive formation in the presence of a fluid system characterized by having a hydrostatic pressure equal to or less than the formation pressure to minimize or eliminate the formation of a filter cake on the formation face, so called under balanced or near balanced drilling. After the productive interval is drilled, a casing string including at least one and preferably a plurality of laterally extendable members having a sand control medium associated therewith is run into the well so that the members can be deployed to contact sites in the productive interval, i.e., the extendable members are positioned and aligned within the productive formation interval of the well. After the casing has been properly run into the well, the members are extended such that each member comes into contact with the filter cake and/or the productive formation at their associated sites, where the contacting in sufficient to allow productive formation fluids to flow through the member into the casing and out of the well. Once the members are deployed forming production conduits between an interior of the casing and the formation, the casing is cemented in place. After casing cementing, production tubing/equipment is run into the well borehole and the well is placed on production. [0017] The present invention provides a method of well construction and completion including the steps of drilling a first interval of a well through non-productive formations in the presence of a first fluid system. Prior to drilling into or into and through a productive formation, the first drilling fluid is replaced with a second fluid system adapted to control fluid loss, to be substantially non-damaging to the productive formation, and to form a filter cake having substantial flow back properties minimizing adverse affects on formation productivity. After fluid system replacement, a second interval of the well is drilled into or into and through a productive formation in the presence of the second fluid system. After the productive interval is drilled, a casing string including at least one and preferably a plurality of laterally extendable members having a sand control medium associated therewith is run into the well so that the members can be deployed to contact sites in the productive interval, i.e., the extendable members are positioned and aligned within the productive formation interval of the well. After the casing has been properly run into the well, the members are extended such that each member comes into contact with the filter cake and/or the productive formation at their associated sites, where the contacting in sufficient to allow productive formation fluids to flow through the member into the casing and out of the well. Once the members are deployed forming production conduits between an interior of the casing and the formation, the casing is cemented in place. After casing cementing, production tubing/equipment is run into the well borehole and the well is placed on production. [0018] The present invention provides a method of well construction and completion including the steps of drilling a first interval of a well through non-productive formations in the presence of a first fluid system. Prior to drilling into or into and through a productive formation, the first drilling fluid is replaced with a second fluid system characterized by having a hydrostatic pressure equal to or less than the formation pressure to minimize or eliminate the formation of a filter cake on the formation face. After fluid system replacement, a second interval of the well is drilled into or into and through a productive formation in the presence of the second fluid system, so called under balanced or near balanced drilling. After the productive interval is drilled, a casing string including at least one and preferably a plurality of laterally extendable members having a sand control medium associated therewith is run into the well so that the members can be deployed to contact sites in the productive interval, i.e., the extendable members are positioned and aligned within the productive formation interval of the well. After the casing has been properly run into the well, the members are extended such that each member comes into contact with the filter cake and/or the productive formation at their associated sites, where the contacting in sufficient to allow productive formation fluids to flow through the member into the casing and out of the well. Once the members are deployed forming production conduits between an interior of the casing and the formation, the casing is cemented in place. After casing cementing, production tubing/equipment is run into the well borehole and the well is placed on production. [0019] The methods of this invention can also include steps designed to remove or reduce the filter cake deposited on the formation face during the drilling operation by pumping a solvent into the well for a time sufficient to remove some or substantially all of the filter pack. The filter pack removal step can occur before or after member extension or before or after well cementing. [0020] The present invention further provides a completed well including a casing string including at least one and preferably a plurality of extended members having a sand control medium associated therewith, where the members extend out from the casing and contact sites in a productive formation forming production conduits through which formation fluid flow into an interior of the casing and out of the well. The member includes a casing fitting, an inner sleeve having inner sleeve stops and an outer sleeve having outer sleeve stops, where the sleeves are movable from a retracted state to an extended state when a sufficient hydraulic pressure is applied to the members. DESCRIPTION OF THE DRAWINGS [0021] The invention can be better understood with reference to the following detailed description together with the appended illustrative drawings in which like elements are numbered the same: Continue reading... 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