354 results about "Effective stress" patented technology

A method of determination of fluid pressures in a subsurface region of the earth uses seismic velocities and calibrations relating the seismic velocities to the effective stress on the subsurface sediments. The seismic velocities may be keyed to defined seismic horizons and may be obtained from many methods, including velocity spectra, post-stack inversion, pre-stack inversion, VSP or tomography. Overburden stresses may be obtained from density logs, relations between density and velocity, or from inversion of potential fields data. The seismic data may be P-P, P-S, or S-S data. The calibrations may be predetermined or may be derived from well information including well logs and well pressure measurements. The calibrations may also include the effect of unloading. The determined pressures may be used in the analysis of fluid flow in reservoirs, basin and prospect modeling and in fault integrity analysis.

The invention relates to a test method for simulating the shear resistant strength change of foundation pit precipitation soil. The test method comprises the following steps of: firstly, preparing an original-shape soil sample by using a fret saw, a soil cutter, a soil cutting disk, and the like; secondly, carrying out exhausting and water injection on the sample in a vacuum tank to be saturated;thirdly, mounting a test sample in which a latex film is sleeved in a three-axle pressure chamber; fourthly, solidifying the test sample at two phases through a three-axle ambient pressure system, wherein the test sample is restored to be in a natural self-weight stress state of a soil body by using the first-time solidification and the stress state of the soil body subjected to precipitation is simulated by using secondary solidification; fifthly, carrying out an un-drained shear test on the test sample through an axial loading system; and sixthly, after the test is ended, closing a motor and a valve and detaching the test sample. According to the test method disclosed by the invention, the influence of the reduction for water content of the foundation pit precipitation soil, the increase of effective stress and soil solidification and compaction on the soil shear resistant stretch is considered so as to provide reference for accurately selecting shear resistant strength indexes of the foundation pit precipitation soil and further provide guarantee for designing and constructing deep foundation pits of soft soil water-rich stratum safely, economically and reasonably.

The invention discloses a shale gas reservoir gas diffusion coefficient experiment test method. According to a method, a one-dimensional diffusion mathematic model is built by monitoring pressure attenuation data in a shale plunger rock sample under effective stress conditions of methane gas with a certain initial pressure in a constant-temperature closed system with the micro-pore structure and the gas existence state of a shale reservoir as bases, the diffusion coefficient of the gas (methane) in shale is calculated, and the diffusion mass-transfer capacity of the gas (methane) in the shale is quantitatively assessed. In the experiment testing process, the diffusion process of gas in the shale gas reservoir can be effectively simulated, and influences of effective stress, gas adsorption / desorption and other factors on the diffusion coefficient are reflected. Besides, the method can overcome influences of gas free expansion stage data in a traditional adsorption / desorption method on the diffusion coefficient. The method can assess the diffusion mass-transfer capacity of the gas in the shale and provide experiment support for researches in the aspects of shale gas reservoir productivity models, productivity prediction and the like.

Determination of in-situ rock yield stress state of a geological formation surrounding a borehole includes determining a profile for each of an axial effective, a radial effective, and a hoop effective stress within at least one axial plane containing a borehole axis. A predicted radial shear response radial profile is calculated from the effective stresses within the at least one axial plane. A measurement-based estimate of a shear response radial profile within the at least one axial plane is determined from measured data. A maximum radial distance at which a difference between the predicted and measurement-based shear response radial profiles is identified within the at least one axial plane as being greater than a difference threshold. The respective axial, radial, and hoop stresses, are determined at the identified maximum radial distance. The identified stresses are indicative of an in-situ yield stress state of the rock.

The invention discloses a method for predicting carbonate formation pore pressure by using log information. The method for predicting the carbonate formation pore pressure by using the log information is based on the effective stress theorem; and by establishing a framework longitudinal wave velocity and pore fluid longitudinal wave velocity equation, a carbonate formation pore pressure equation is established, so that the carbonate formation pore pressure is detected according to the measured log information, scientific evidences are provided for determining safety drilling fluid density during drilling design, and carbonate formation underground complex accidents in the construction process are effectively prevented.

The invention discloses an underground coal seam hydrofracture crack oriented developing method which comprises the following steps: (1) drilling into a hydrofracture drill hole and oriented drill holes, wherein the number of the hydrofracture drill hole is one, the oriented drill holes are arranged around the circumference circle at intervals, and respectively conducting water jet cutting to the hydrofracture drill hole and all oriented drill holes, wherein water jet cutting is achieved through a high-pressure water jet cutting device; (2) respectively conducting hole sealing to the hydrofracture drill hole and all oriented drill holes; and (3) conducting hydraulic fracturing to the hydrofracture drill hole. According to the underground coal seam hydrofracture crack oriented developing method, secondary disasters of a coal seam top base plate caused by disordered developing of cracks can be avoided, meanwhile, effective stress in the hydrofracture area can be reduced, closing of the cracks is retarded, flow conductivity of the cracks is strengthened, and therefore the purposes of effectively managing gas and efficiently pumping and exploiting the gas can be achieved.

The invention discloses a method for calculating formation pressure based on petrophysical parameters, and uses well measurement data of a velocity of a P-wave VP, a velocity of a shear wave VS, a density Rho and a porosity Phi of formation. The method comprises the following steps: deriving a ratio value between a bulk modulus Kdry of a dry rock and a bulk modulus Kma of a rock matrix material by using a Gassmann equation; calculating an effective bulk modulus Kma of a mineral component according to a V-G-H model, calculating a bulk modulus Kf of a pore fluid according to a Wood model to calculate an effective stress coefficient Alpha and an Skempton coefficient B; and estimating the formation pressure according to an effective stress between the Skempton coefficient B and a porous media, the effective stress coefficient Alpha and the Skempton coefficient B. The method is suitable for a mixed lithology and a single lithology, the formation pressure is estimated without relying on a conventional under compaction theory of a mudstone or a shale, so that the calculated formation pressure is more close to real formation pressure.

Embodiments of the invention operate to produce basin models that describe the basin in terms of compaction and fluid flow. The equations used to define compaction and fluid flow may be solved simultaneously. Embodiments of the invention use equations that define a set of unknowns that are consistent over the basis. The equations may define total pressure, hydrostatic pressure, thicknesses, and effective stress.

The invention discloses a method and device for determining formation pressure. The method includes the steps that amplitude preservation processing is carried out on longitudinal wave PP and converted wave PS seismic data so that superposition data of multiple portions can be obtained, and a longitudinal wave impedance body, a transverse wave impedance body and a density body are obtained in a pre-stack PP and PS joint simultaneous inversion method according to logging information; the longitudinal wave impedance body, the transverse wave impedance body and the density body are converted into depth domains; pressure of overlying strata is calculated according to the density body; effective stress of a framework is calculated according to the longitudinal wave impedance body, the transverse wave impedance body and the density body; the formation pressure is calculated according to the pressure of the overlying strata and the effective stress of the framework. Precision of formation pressure seism prediction can be improved.

The invention discloses a method for recognizing sweet spots in a shale stratum. The method includes the following steps that the kerogen volume content, the gas-bearing porosity, the gas saturation and the total organic content of the shale stratum are determined according to logging information, and the geological sweet spot coefficient of the shale stratum is obtained through a radar map analyzing method; the maximum horizontal effective stress value, the pore structure index and the brittleness index of the shale stratum are determined according to the logging information, and the engineering sweet spot coefficient of the shale stratum is obtained through the radar map analyzing method; and the sweet spots in the shale stratum are recognized according to the geological sweet spot coefficient and the engineering sweet spot coefficient. According to the method, the geological sweet spots and the engineering sweet spots in the shale stratum are quantitatively represented according to the geological sweet spot coefficient and the engineering sweet spot coefficient, and the sweet spots in the shale stratum can be determined through comprehensive analysis of the two coefficients; and the development cost can be lowered by exploration and development in sweet spot areas, and the development efficiency of shale gas is improved.

The invention discloses a method for testing gas-water relative permeability of a dense core. The method comprises the following steps: (1) preparing an experimental core, measuring the porosity and the klinkenberg permeability of the core, and determining the minimum return pressure of weakening a slippage effect; (2) establishing water saturation in the core by utilizing formation water or simulation formation water; (3) arranging the core in a core holding unit, applying confining pressure to the original effective stress or reservoir overburden pressure and constant displacement pressure p1, applying return pressure p2 at the core outlet, and measuring the gas flow of the core; (4) measuring the gas flow of the core under different water saturations, and calculating the gas-phase effective permeability and gas-phase relative permeability of the core; (5) establishing 100 percent of water saturation in the core, and measuring the accumulated water yield of the core in unit time; and (6) calculating the water-phase effective permeability and water-phase relative permeability of the core. The method disclosed by the invention can be used for really reflecting the gas seepage conditions under in-situ conditions and simulating the underground production state and has wide market prospects.

The invention discloses an effective stress level test device and method of a vertical prestressed reinforcement. An ARM (Advanced RISC Machines) processor is connected with an ultrasonic pulse generator; a pulse signal emitted from the ultrasonic pulse generator is transmitted to an ultrasonic transducer via a boosted circuit and a transmitter circuit; the ultrasonic transducer transmits the ultrasonic wave to a data register via a programmable filter, a programmable amplifier and an A / D (analog-to-digital) converter; collected signals are sent to a DSP (Digital Signal Processor) by the data register; the DSP stores the signals in an RAM (Random-Access Memory) storage area; the ARM processor is connected with a memory, a keyboard, a display, the programmable amplifier, the programmable filter, the RAM storage area and a temperature measurement circuit; and the temperature measurement circuit is connected with a temperature sensor. The device has the characteristics of no loss, high speed, high accuracy and low cost, especially can quantify the influence of temperature on a stress measurement result, can correct the stress level test error of the vertical prestressed reinforcement so as to obtain the effective stress level value of the vertical prestressed reinforcement with the engineering accuracy.

Method for constructing an integrated rock physics model that simulates both shale anisotropy and stress-induced anisotropy of clastic rocks. In the model, the total pore volume is divided into three parts according to the estimated shale volume and effective stress: (1) clay-related pores, (2) sand-related pores, and (3) microcracks (mainly in the sand component). The pore space is then partitioned into the clay-related and sand-related pores using a scheme first disclosed by Xu and White in 1995. The model simulates shale anisotropy via the preferred orientation of clay-related pores and stress-induced anisotropy via the preferred orientation of microcracks, which is controlled by the differential stresses. Laboratory measurements or well logs are needed to establish a relationship between crack density and the effective stress.

The invention provides a sand shale rock reservoir stratum pressure earthquake prediction method and device; the method comprises the following steps: calculating the elastic modulus, the microfissure density and microfissure closed rate factors under the limited effective stress according to a Hashin-Shtrikman boundary model and the porosity and shale content of an object sand shale rock reservoir in a research zone; determining the relation between the dry rock elastic modulus and effective stress according to the elastic modulus, the microfissure density and microfissure closed rate factors; determining the effective stress coefficient of the sand shale rock along with the depth changes according to said relation; predicting the stratum pressure of a single well to-be-detected object layer according to said relation and the effective stress coefficient; using an elastic modulus data body obtained by inversion and taking the single well stratum pressure as constraints, and carrying out three dimensional earthquake stratum pressure prediction on the research zone according to said relation and the effective stress coefficient. The method and device can improve the stratum pressure prediction accuracy.

The invention discloses a fatigue life prediction method for a friction stir welded component based on small crack propagation, and belongs to the technical field of fatigue diagnosis and analysis ofmechanical structures. The method comprises the steps that a bone-shaped flat plate sample is prepared, fatigue small crack propagation replica tests under different stress loads and different stressratios are conducted on different areas of a joint, and a secant method is adopted for calculating the propagation rate of small cracks; a New-Raju model is adopted for calculating the stress intensity factor range of the small cracks of the joint; c values in the depth direction and a / 2 values in the vertical direction of semi-arc shapes of fatigue crack propagation zones in fracture shapes of different areas of the joint, and the depth-to-length ratio 2c / a of the cracks is calculated; a curve of the propagation rate of the cracks along with the change of the stress intensity factor range isdrawn; an effective stress intensity factor is calculated; a formula of the propagation rate of the small cracks is determined; an initial crack size a0 and a critical crack size ac are determined; the formula of the propagation rate of the small cracks is integrated to obtain the fatigue life of the welded component. By means of the scheme, the fatigue life of the friction stir welded component can be more easily and accurately predicted.

The invention discloses a method for predicting vertical well volume fractured reservoir reform volume of low permeable reservoir. The method sequentially comprises the following steps: (1) calculating the induced stress produced by hydraulic fracture in a three-dimensional space; (2) calculating the formation pore pressure obtained after leak-off of fracturing fluid; (3) calculating the formation pore elastic stress obtained after the leak-off of the fracturing fluid; (4) overlapping the stress fields obtained in the step (1), (2) and (3) with an in-situ stress field to obtain a new crustal stress field, and calculating the magnitude and direction of three-way principal effective stress in the overlapped reservoir space; (5) calculating the open fracture determination coefficient M of a natural fracture in the reservoir space and the shear fracture region determination coefficient S of the natural fracture so as to predict the volume fractured reservoir reform volume. The method is used for predicting the reservoir reform volume after vertical well volume fracturing, is better in operability and accuracy, provides a favorable theoretical basis for effect evaluation and yield prediction after vertical well volume fracturing of the low permeable reservoir, and overcomes the defects of the prior art.

The invention discloses a method for determining an effective rock stress coefficient based on a pore compression experiment. The method comprises the following steps: selecting cores with similar physical properties in the same direction of the same rock, vacuumizing saturated fluid, gradually increasing triaxial confining pressure under the condition that the pore pressure is maintained to be room pressure, measuring the volume of fluid discharged from pores in the pressurization process, determining the rock pore compression coefficient, fitting a fitting function between the effective stress and the pore compression coefficient, measuring a pore pressure constant value of the saturated core and the pore pressure value after the confining pressure is increased, determining core pore volume reduction, and finally determining the effective rock stress coefficient value according to a calculation formula of the effective stress born by a rock matrix and the rock pore compression coefficient. The method is applied to low-permeability and ultralow-permeability reservoir stress research, the testing equipment is simple, the principle is clear, and the method is simple and accurate in measurement result.

The invention discloses an evaluation method for unconventional reservoir volume transformation multi-pore media productivity contribution. The evaluation method comprises the following steps that firstly, based on the principle of effective stress and flow characteristics of a transformation zone, and a fluid-solid coupling mathematical model of interaction between a geotechnical deformation field (stress field) and a fluid flow field (seepage field) of the unconventional reservoirs is established; then a perfectly coupled method solution of the seepage field and the stress field is realizedby solving a fluid-solid perfectly coupled system of partial differential equations in a general formula mode; and finally, fluid-solid coupling interactions under different combinations of pore mediaare simulated, and the contribution ratio of three systems of base materials, natural cracks and grid cracks to the cumulative production of a volume transformation well is obtained. A set of evaluation method for unconventional reservoir volume transformation multi-pore media productivity contribution is established eventually. The evaluation method for unconventional reservoir volume transforming multi-pore media productivity contribution has the advantages that the model factor consideration is comprehensive, the evaluation method is simple and results are quantifiable, an oil and gas field can be guided timely to be subjected to development measure adjustment and comprehensive management, and a theoretical basis and technical support are provided to the unconventional reservoir to realize economic recovery.

The invention discloses a material breakage constraint-based continuum structure topology design modeling and optimization design method, which is used for solving (a) problems of stress concentration and singularity, and (b) a problem of maximum stress fluctuation and a problem of high analyzed and calculated quantity in different degrees in the prior art. In the method, effective stress constraint relaxation is adopted to treat the phenomenon of stress singularity. In the process of optimizing problem approximation modeling, a q1 norm metrical function of the structural stress serves as a penalty function, all unit stress constraints are replaced by q2 norm metrical function constraint of the structural stress, the most potential active unit stress constraints and the introduced volume constraints, and the local stress level is controlled by combining variable constraint limit. The optimization process of the method is divided into two optimization stages and a conversion stage, and the design space is automatically expanded and reduced. A quadratic programming method is utilized to solve each stage, a pure optimized structural topology in black / white distribution can be obtained, and the method has high optimization design efficiency.

The invention provides a testing apparatus for simulating a soil piping failure development process and a testing method thereof. A variable head water supply system is connected with the bottom of atransparent model case through a feed pipe, a water outlet pipe is arranged at a top of the transparent model case, and a multilayer porous cover plate is spread at the bottom of the transparent modelcase; a saturated transparent soil sample is arranged over the multilayer porous cover plate, a fluorescent agent is added in aperture fluid in the variable head water supply system, a laser is placed outside the transparent model case, a CCD camera is placed outside the transparent model case, and aperture pressure measurement apparatuses are equidistantly arranged in the transparent model case.The effective aperture distribution curves and effective stress distribution under penetration fluid effect of the soil are used for determining whether the soil generates piping failure or not, andthe testing apparatus provides basis for reasonable design of water conservancy structure and geotechnical engineering.

The invention discloses a hydrate sediment flow solid output measuring device combining an X-CT technology and a measuring method. The measuring device comprises an X-ray penetration type reaction kettle, an X-CT scanning analysis system, a vacuum system, a temperature and pressure control system, a hydrate sample preparation system, a sand production monitoring system and a permeability measuringsystem, wherein through integrated application of a sand production-seepage system under the micro-scale multi-factor coupling effect, the coupling relationship of a reservoir structure and physicalspace-time evolution and flow solid output under the multi-factor collaborative action can be quantitatively described, different hydrate generation modes can be selected according to the experiment requirements, different hydrate occurrence states in natural sediments can be simulated and studied, and the device and the method can be used for researching the space-time evolution characteristics of a sediment pore structure under the hydrate convergence and divergence and effective stress conditions and an influence rule of the space-time evolution characteristics on sediment flow solid output, so that the theoretical bottleneck of the hydrate reservoir structure and a physical evolution and flow solid output mechanism in a hydrate production process is broken through, and the device and the method have important engineering significance to deeply understand a depressurizing production law of the South China Sea, practically improve the biogas production efficiency and perfect a depressurizing production technology system.

The invention relates to an evaluation method for reliable life of blade vibration fatigue of a gas compressor impeller of an automotive turbosupercharger. The method comprises the following steps: firstly, the operation condition of the automotive turbosupercharger and the working state parameters of the gas compressor impeller are determined; then, the dangerous parts of the blade vibration fatigue of the gas compressor impeller and the stress parameters of every corresponding working condition are determined; then, the fatigue strength of the dangerous parts of the blade vibration fatigue of the gas compressor impeller is determined by adopting a test method to compare the magnitude relation between the equivalent stress of the dangerous parts of the blade vibration fatigue of the gas compressor impeller and the fatigue limit of the blades under different working conditions and determine the effective stress parameters for evaluating the blade vibration fatigue life of the gas compressor impeller; the probability distribution characteristics of the blade vibration fatigue life of the gas compressor impeller and the reliable life meeting different reliability requirements are determined. The method can evaluate the reliable life of the blade vibration fatigue of the gas compressor impeller in the development stage of the turbosupercharger, and can preferably guide the structural design and reasonable use of the gas compressor impeller.

The invention provides a mini three dimensional effective stress box. The mini three dimensional effective stress box is characterized in that a skeleton of the stress box is in an upper-middle-lower structural form; the middle structure is an eight-prism which is formed by means of enclosure of eight squares; the upper and lower structures are formed by five squares or four equilateral triangles; the upper structure and the lower structure are symmetrical with the middle structure; an inclinometer is arranged on any surface of the inner wall of the skeleton; bearing diaphragms are respectively arranged on each surface, with round holes, of the skeleton; a foil gauge is pasted on the inner wall of the round surface which is formed after combination of the bearing diaphragms and the skeleton; and a foil gauge wire and an inclinometer wire are led out through a data wire hole by means of a data wire, and then are connected with a data acquisition instrument so as to form a mini three dimensional effective stress box. And at the same time, the invention also provides a test method of the mini three dimensional effective stress box. The mini three dimensional effective stress box and the test method of the same have the advantages of reducing the error caused by rotation of the mini three dimensional effective stress box, reducing the test error caused by unequal range finding, being able to reflect the bearing state of soil because of improvement of accuracy, improving the safety stock during the soil construction process.

The invention discloses an abnormal formation pressure calculation method. The method includes: acquiring first effective stress through the relation between Young modulus and longitudinal and transverse wave velocity; acquiring second effective stress through the relation between bulk modulus and the longitudinal and transverse velocity; subjecting the first effective stress and the second effective stress to weighted average to acquire a final effective stress result; according to the final effective stress result, determining abnormal formation pressure sections by the aid of the effective stress theory. With the method, precision in predicting formation pressure is improved, influence of containing gas in the formation on formation velocity is eliminated, a high-precision model is established between the formation velocity and the effective stress, and an elastic modulus weighing method is developed to have the formation pressure predicated.

The invention discloses a method for determining effective stress coefficients of a rock. The method comprises the steps of preparing a rock test sample and measuring and recording the size of the rock sample; loading the rock sample into a pressure chamber of a triaxial servometer, loading confining pressure to a predetermined value, keeping the confining pressure, constantly loading bias, loading the bias to a set value, unloading, keeping the bias and the confining pressure constant and loading pore water pressure; repeating the previous step and loading the bias until the rock sample is destroyed; drawing a relation curve of bias increments and axial / circumferential strain increment under different confining pressure and carrying out data fitting on the curve to obtain an effective elastic modulus E1 and poisson ratio v31 related to bias grades; and calculating an axial effective stress coefficient and a circumferential effective stress coefficient of the rock sample through a formula. The effective stress coefficients obtained through the method are accurate and reliable, and can be applied to numerical calculation of seepage and stress coupling in practical engineering, the calculation accuracy is greatly improved and the analysis error is reduced.

The invention discloses a method for detecting limestone formation pore pressure, which is applied in the technical field of oil field drilling, and comprises the following steps of sampling rock mechanics parameter data of sampled well rocks with a same geologic structure, establishing an effective stress model, requesting feature data of overlying rock pressure and depth, establishing an overlying rock pressure model, establishing a detection model of the limestone formation pore pressure and detecting the limestone formation pore pressure. The method has the benefits of having a higher fitting degree and better trend compliance, and basically solving the difficulty that a traditional method is not applicable to the detection on the limestone formation pore pressure compared with formation pore pressure data actually measured in field.

The invention relates to an experimental evaluation method suitable for coal-bed fracturing fluid flow filtration. The method comprises the following steps of: loading effective stress corresponding to burial depth to a core holder connected with a fracturing fluid cavity; stirring the fracturing fluid in the fluid cavity to allow the fracturing fluid to flow through the front end face of a core at a certain flow speed; pressurizing the fluid cavity by using a constant pressure pump to form a certain pressure difference between the front end and the back end of the core; and measuring the filtration loss and corresponding filtration time of filtrate at the outlet end of the core. A fracturing fluid filtration situation in a coal-bed yield-increasing and modifying process is simulated, and the scientific and effective measurement of the filtration property of the fracturing fluid which does not contain any propping agent under a formation condition is realized.

The invention discloses a method for recognizing engineering sweet spots in a shale stratum. The method includes the following steps that the maximum horizontal effective stress value of the shale stratum is determined according to sound wave and density logging information and dipole sound wave logging information; the pore structure index of the shale stratum is obtained according to imaging logging information and physical parameters; the brittle mineral content in the shale stratum is determined based on element logging information and is used for determining the brittleness index of the shale stratum; and according to the maximum horizontal effective stress value, the pore structure index and the brittleness index of the shale stratum, the engineering sweet spot coefficient of the shale stratum is determined through a radar map analyzing method, and the engineering sweet spot coefficient is used for recognizing the engineering sweet spots in the shale stratum. By analyzing the engineering sweet spot coefficient of the shale stratum, it is determined that the brittleness index, the maximum horizontal effective stress value and the pore structure index are the main parameters of the engineering sweet spots in the shale stratum, and the engineering sweet spots in the shale stratum can be accurately recognized according to the existing logging information.