353 results about "Fracture pressure" patented technology

According to the present invention, a composition and method for hydraulically fracturing a subterranean formation is provided. The composition comprises an aqueous mixture of a hydrated polysaccharide, preferably a galactomannan gum, the hydrated polysaccharide having a plurality of bonding sites; a crosslinking agent for crosslinking the hydrated polysaccharide at the bonding sites at the conditions of the subterranean formation with a polyvalent metal ion to form a polyvalent metal crosslink, thereby increasing the viscosity of the hydrated polysaccharide; and a controlled solubility compound for releasing a chelating agent for controllably breaking the polyvalent metal crosslink and bonding with the polyvalent metal ion released by breaking the crosslink, thereby decreasing the viscosity of the hydrated polysaccharide. The method comprises the steps of injecting the above-described composition into the subterranean formation at fracturing pressures; allowing the controlled solubility compound to begin breaking the polyvalent metal crosslink, thereby reducing the viscosity of the hydrated polysaccharide and yielding a lower viscosity fluid; and removing the lower viscosity fluid from the subterranean formation.

A Drill-To-The-Limit (DTTL) drilling method variant to Managed Pressure Drilling (MPD) applies constant surface backpressure, whether the mud is circulating (choke valve open) or not (choke valve closed). Because of the constant application of surface backpressure, the DTTL method can use lighter mud weight that still has the cutting carrying ability to keep the borehole clean. The DTTL method identifies the weakest component of the pressure containment system, such as the fracture pressure of the formation or the casing shoe leak off test (LOT). With a higher pressure rated RCD, such as 5,000 psi (34,474 kPa) dynamic or working pressure and 10,000 psi (68,948 kPa) static pressure, the limitation will generally be the fracture pressure of the formation or the LOT. In the DTTL method, since surface backpressure is constantly applied, the pore pressure limitation of the conventional drilling window can be disregarded in developing the fluid and drilling programs. Using the DTTL method a deeper wellbore can be drilled with larger resulting end tubulars, such as casings and production liners, than had been capable with conventional MPD applications.

A system and method for safely controlling a well being drilled or that has been drilled into a subterranean formation in which a conventional blow-out preventer operates to close the well bore to atmosphere upon the detection of a fluid influx event. Fluid pressures as well as fluid flow rates into and out of the well bore are measured and monitored to more accurately and confidently determine the fracture pressure and pore pressure of the formation and perform well control operations in response to a fluid influx event. During a suspected fluid influx event, one or more of the fluid flow and pressure measurements are used to confirm the fluid influx event and to safely regain well control by circulating the fluid influx out of the well through a choke line while maintaining the pressure inside the well between specified, selected limits, such as between the fracture and pore pressures.

The present invention relates to a shale gas reservoir crustal stress logging prediction method based on a rock physics model. According to the method, a shale gas reservoir rock physics model which takes kerogen particles into consideration is established, so as to predict a longitudinal and transverse wave velocity of the logging; based on the above, a maximum and minimum horizontal principal stress and a fracture pressure of the reservoir are calculated; and an accurate stress assessment of a shale gas reservoir is carried out while a transverse wave logging is not provided. The beneficial effects of the invention are that: the rock physics model in line with characteristics of the shale gas reservoir is established to improve precision of the prediction velocity; and based on the rock physical model, the maximum and minimum horizontal principal stress and the fracture pressure are obtained, so that while the measured transverse wave logging data are not provided, the underground stress can be predicted on the basis of a conventional logging curve, and the prediction result is high in accuracy.

The invention relates to a directional fracturing method in the coal mine and a fracturing permeability improvement outburst elimination device to ensure the coal-bed gas to release rapidly and continually in the coal mine. The method comprises the following steps: fracturing and drilling a bore on a preparing working face along the dip direction and strike direction of a coal bed, fixing a fracturing hole packer with an outer diameter matching with the pore diameter of a fracturing drilling bore into the fracturing drilling bore; connecting a fluid reservoir with a sand mixing machine, connecting the sand mixing machine with a fracturing pump package, and then connecting the fracturing pump package with the fracturing drilling bore; pumping formation fracturing fluid and proppant into the fracturing drilling bore to fracture the formation and sealing the fracturing drilling at above formation fracturing pressure, and completing directional fracturing permeability improvement outburst elimination in the coal mine, thus ensuring that the coal-bed gas discharges rapidly and continually relatively and solving the problems that drainage in low air permeability coal bed can only influence a limited range and the drainage attenuation period is short, improving the drainage rate by over 50% on primary base, decreasing the coal body dynamic phenomenon after fracturing and reginal stress influenced by fracturing, and having a significant effect for eliminating outburst.

A system for reverse circulation in a wellbore include equipment for supplying drilling fluid into the wellbore bit via at least an annulus of the wellbore and returning the drilling fluid to a surface location via at least a bore of a wellbore tubular. The system also includes devices for controlling the annulus pressure associated with this reverse circulation. In one embodiment, an active pressure differential device increases the pressure wellbore annulus to at least partially offset a circulating pressure loss. In other embodiments, the system includes devices for decreasing the pressure in the annulus of the wellbore. For offshore application, annulus pressure is decreased to accommodate the pore and fracture pressures of a subsea formation. In still other embodiments, annulus pressure is decreased to cause an underbalanced condition in the well.

A refracture-candidate diagnostic test is an injection of compressible or slightly compressible fluid such as liquid, gas, or combination at pressures in excess of minimum in-situ stress and formation fracture pressure with pressure decline following injection test recorded to detect a fracture retaining residual width from previous stimulation treatments. The diagnostic consists of small volume injections with injection time being a small fraction of time required for compressible or slightly compressible reservoir fluid to exhibit pseudoradial flow. The fracture-injection portion of a test can be considered as occurring instantaneously, and the results obtained in an open infinite-conductivity hydraulic fracture with pressures above fracture closure stress during before-closure portion of pressure falloff and with pressures less than fracture closure stress during after-closure portion of pressure falloff. Data measurements are transformed into a constant rate equivalent pressure transformation to obtain adjusted pressures or adjusted pseudovariables which are analyzed to identify dual unit-slope before and after closure periods confirming a residual retaining width.

The invention provides a method for calculating the fracture pressure of ultra deep well formations. The method is based on an elastic theory, a pore elastic theory and a thermoelasticity theory, various factors which can influence the calculation precision are comprehensively taken into consideration, and compared with the calculating method of the prior art, the method is utilized for greatly increasing the calculation precision. The difference between a calculation result obtained by a fracture pressure prediction model of the method and the fracture pressure obtained by calculating according to practical field log data is within 10%. The method is particularly suitable for carbonate rock ultra deep well formations.

The invention discloses a method for calculating a tight reservoir fracturing transformation volume area. The method comprises the following steps that multiple hydraulic fracture non-planar turning extension models, a formation stress field change model, a reservoir pressure file change model and a natural fracture failure criterion in the tight reservoir horizontal well fracturing process are established, geological parameters, horizontal well fracturing construction parameters and the total fracturing time are obtained, an initial fracture filter loss value, an initial fracture half-length value, an initial in-fracture pressure value, an initial fracture extension turning angle, initial permeability and an initial fracturing time value are endowed, all the models are calculated, and natural fracture failure point coordinate data is calculated; a spatial and numerical integration method is utilized to calculate tension failure transformation area volume and shear failure transformation area volume in a reservoir respectively, and the spaces of the two parts are united and regarded as a total transformation volume area. By adopting the method, accurate, economic and rapid tight reservoir horizontal well fracturing evaluation can be achieved, and the problem that effort, money and time are wasted in the existing tight reservoir horizontal well fracturing transformation volume area calculating process is solved.

The present invention provides a method for gravel packing a open-hole wellbore having a filter cake, comprising pumping a gravel slurry into a first portion of an annulus between the wellbore and a screen, at a sufficient rate and pressure to form at least a first fracture and diverting the gravel slurry to a second portion of said annulus through alternate flowpaths while providing hydraulic isolation between the first and the second portion of said interval, thereby preventing flowback from said second portion to said first portion and resulting extension of the first fracture, and thereby forming a second fracture in said second portion of said interval.

A method of fracturing a reservoir comprising the steps of pumping a geopolymer precursor fluid through a wellbore into the reservoir at a fracture pressure, the geopolymer precursor fluid at the fracture pressure generates fractures in the reservoir, wherein the geopolymer precursor fluid is comprised of an amount of aluminosilicate, an amount of alkaline reagent, and a permeability enhancer, allowing the geopolymer precursor fluid to fill the fractures in the reservoir, shutting-in the wellbore at a wellbore pressure, the wellbore pressure maintains the geopolymer precursor fluid in the fractures, allowing the geopolymer precursor fluid to harden for a hardening time to form a geopolymer in the fractures, the geopolymer has a geopolymer matrix, the geopolymer matrix has a permeability, the geopolymer has a compressive strength, and reducing the wellbore pressure allows a reservoir fluid to flow from the reservoir through the geopolymer matrix of the geopolymer to the wellbore.

A method of creating multiple fractures in a well traversing a formation is described using pressurized fluids in a highly deviated or horizontal section of the well at a pressure above the fracturing pressure of the formation, wherein for creating a fracture the pressurized fluid is alternated between an acid fracturing fluid and a proppant loaded fluid, such that the proppant blocks the flow of pressurized fluid into a fracture created during a previous step of the method and the subsequently pressurized acid fracturing fluid creates a new fracture at a location along the highly deviated or horizontal section different from the location of the previously created fracture.

It relates to a method of predicting the collapse and crack pressure underground with the drilling head. Recording the earthquake status of a well to be drilled and several other adjacent drills that have already been drilled, getting the earthquake record of the well to be drill and already drilled through weighting, through sound wave echoing difference and density measuring for the already drilled wells to get the log data of different strata, a hierarchical model can be established to predict the sound wave speed and wave resistance of each strata based on the earthquake record. Through the log curve predicted of the strata of the well to be drilled, the collapse and crack pressure of the strata can be predicted combined with the interpretative model of the well wall stability mechanics logging. It can effectively prevent the collapse of the well wall and accidents occurrence underground.

The invention relates to a method and an apparatus for predicting multi-section fracturing productivity of a shale gas reservoir horizontal well. The prediction method comprises: obtaining shale gas reservoir original parameters after fracturing modification; establishing a physical model for a target region by utilizing the shale gas reservoir original parameters, and obtaining a strong form control equation of gas flow in a shale matrix and a strong form control equation of gas flow in a fracture network; establishing a control equation for the gas flow in the shale matrix and a comprehensive control equation for the flow in a fracture system by utilizing the strong form control equation of the gas flow in the shale matrix and the strong form control equation of the gas flow in the fracture network; establishing a strong discontinuous expansion function; substituting the strong discontinuous expansion function to the control equation for the gas flow in the shale matrix and the comprehensive control equation for the flow in the fracture system to calculate fracture pressure distribution; and substituting the fracture pressure distribution into a productivity equation to obtain shale gas productivity.

The invention provides a well drilling thief zone location identification method based on multi-message fusion, and belongs to the field of well drilling exploration. A thief zone can be accurately determined and thief zone property parameters can be accurately calculated according to essential conditions for leakage. The well drilling thief zone location identification method based on multi-message fusion includes the specific steps that (1) according to drilling fluid summaries and comprehensive logging record data, the leakage depth range is locked, and the developed lithology of a formation within the depth range is locked; (2) lithology and physical property parameters within the leakage depth range locked in the first step are explained and calculated through logging information and geologic information; (3) the equivalent circulating density of drilling fluid, the formation pore pressure equivalent density and the formation fracture pressure equivalent density are calculated according to logging and engineering information; and (4) data obtained in the step (1), the step (2) and the step (3) are sorted to draw a comprehensive result map, thief zone location identification is carried out through the comprehensive result map, and the leakage mechanism is analyzed.

The invention discloses a polyvinylidene fluoride hollow fiber ultrafiltration membrane with permanent hydrophilcity and a preparation method thereof. The preparation method comprises the following steps of: sequentially adding 13 wt% to 25 wt% of polyvinylidene fluoride, 8 wt% to 16 wt% of additives and 0.02 wt% to 3.0 wt% of surface active agents and solvents in a dissolving tank, and then stirring for dissolving for 2 to 16 hours at 15 to 90 DEG C to the fully uniform state to prepare that initial membrane casting liquid; sequentially adding initiating agents accounting for 0.1 wt% to 3.5 wt% of polar monomers and the polar monomers accounting for 0.1 wt% to 5.0 wt% of the membrane casting liquid in the membrane casting liquid, and reacting for 1 to 12 hours at 15 to 90 DEG C to prepare hydrophilic membrane casting liquid; and preparing the hydrophilic hollow fiber ultrafiltration membrane by adopting the traditional dry-wet spinning technology. For the hydrophilic polyvinylidene fluoride hollow fiber ultrafiltration membrane prepared in the preparation method, the pure water permeability coefficient is greater than 230 L/m2*hr*0.1MPa, the retention rate of bovine serum albumin (67000MW) is greater than 95.0%, the breaking elongation rate of fibers is greater than 200%, and the fracture pressure is greater than 0.55 MPa. The polyvinylidene fluoride hollow fiber ultrafiltration membrane with permanent hydrophilcity is especially suitable for deep treatment and recycling of waste water, clarification and separation in the fields of biochemical engineering and medicament, and the like.

The invention discloses a volume fracturing method of deep shale gas multi-scale proppant packing. The volume fracturing method of deep shale gas multi-scale proppant packing comprises the following steps: (1) evaluating key engineering parameters of shale gas; (2) determining a fracturing fluid system and a proppant; (3) optimizing fracture parameters and fracturing construction parameters; (4) determining the position of a fracturing section shower hole and perforating parameters; (5) carrying out acid pretreatment; (6) carrying out low viscosity quick water low-displacement fracture heightcontrolling fracturing; (7) carrying out ultra low density proppant screen-out fracturing; (8) carrying out multi-scale fracture fracturing packing; and (9) according to a hole volume of each fracturing section, carrying out over-displacing operation according to 110-120%. The volume fracturing method of deep shale gas multi-scale proppant packing, disclosed by the invention, has the advantages that the net pressure is effectively increased by combining processes of optimizing acid treatment to reduce a fracture pressure, carrying out low viscosity quick water low-displacement injection fracture height controlling, screening out in a mixed ultra low density proppant fracture and so on, and through full-process small particle size proppant injection construction, the filling degree of the deep shale gas fracture system of small and micro fracture development is enhanced. Therefore, the effective volume of the fracture is further increased, and the long-time fracture flow conductivity isfurther improved.

A welihead assembly to seal to a production casing including one or more pressure-containing wellhead body members defining a vertical bore, with the lowermost of the wellhead body members sealing to the production casing. A fracturing isolation tool is sealed in the vertical bore of the wellhead body members above the production casing, and forms a pressure barrier profile in its internal bore. A removable protector sleeve is located at least partially within the fracturing isolation tool to seal, protect, isolate and cover the pressure barrier profile against a fracturing pressure and a fracturing fluid. After fracturing the protector sleeve is removed and a pressure barrier is sealed in the pressure barrier profile of the fracturing isolation tool. The invention also extends to the method of isolating the wellhead body members and to the fracturing isolation tool assembly which includes the fracturing isolation tool and the protector sleeve.

A method for preventing soil fracture and/or monitoring borehole pressure during jet grouting that may include monitoring borehole pressure at one or more points in a jet grouting borehole while the jet grouting is being performed and determining whether the borehole pressure exceeds a predetermined limit. The method may further include providing notification to a jet grouting operator that there is a high risk of soil fracture if the borehole pressure exceeds the predetermined limit. The predetermined limit may be the estimated fracture pressure of the soil in which the jet grouting is being performed.

The invention relates to a method for determining formation fracture pressure gradient logging of a shale gas reservoir. The method comprises the following steps of calculating formation fracture pressure gradient of an objective layer of the shale gas reservoir by evaluating according to layers or according to certain step length in the layers; acquiring formation hole fluid pressure gradient of the objective layer through logging or well measuring information; acquiring the rock poisson ratio of the objective layer through logging or indoor core experimental analysis information; acquiring gas saturation through logging or well measuring information; acquiring overlaying formation lithology density through well measuring information; calculating the formation fracture pressure gradient FRAC of the shale gas reservoir according to the formula: FRAC=FPG+POIS/(1-POIS)*(DENb-Sg*FPG); and outputting a result according to a formula: FP=FRAC*H/100. The method is applied to 32 shale gas wells in the Jiannan gas field of the middle yangtze region, the shale gas field of the Fuling region, the western Hunan region and the western Hubei region; and the error of a calculated value and the actually acquired formation fracture pressure gradient is &1t;10%.