413 results about "Natural fracture" patented technology

The invention relates to an oil-gas well hydraulically-created-fracture expansion visualization experiment method and an oil-gas well hydraulically-created-fracture expansion visualization experiment device. The device is composed of a rock sample chamber, a crustal loading unit, a simulation fracturing string, a high-speed camera, a high-pressure pumping unit, a data measuring and collecting unit and the like, and four transparent observation ports are formed on a top cover of the rock sample chamber. The method includes firstly, preparing a flat-plate-type rock sample, performing high-pressure-water cutting to preform a natural fracture, and filling the natural fracture with epoxy resin to form a filled-type fracture; secondly, performing water saturation on the rock sample for 3-5 days, and using epoxy resin to wrap the rock sample after water saturation; thirdly, loading three-axis stress on the rock sample, drilling a borehole under the condition that the three-axis stress is applied on the rock sample, and mounting the simulation fracturing string; finally, connecting a high-pressure pipeline with a constant-flux pump, pumping fracturing liquid, recording a fracture expansion path by the high-speed camera, and measuring pumping pressure changes by a pressure transmitter. By the method and the device, the hydraulically-created-fracture expansion path can be visualized on a plane, and a novel experiment method is provided for studying on a hydraulically-created-fracture expansion mechanism.

A method of treatment of subterranean formations in which leakoff through natural fractures is controlled through the use of fibers. The method involves pumping a mixture of a formation treatment fluid and a fiber into the formation for matrix stimulation, fracture stimulation, diversion, and / or water control. In carbonate formations, the formation treatment fluid is preferably an in situ gelled acid. The method optionally also involves pumping the same or a different formation treatment fluid without fiber.

A method for predicting localized damage and naturally occurring fractures in a subsurface region is provided. This invention uses a hybrid FEM-DEM (i.e. finite-discrete element) framework combined with a fracture risking analysis and fracture initiation and propagation criteria, to model the transition of rock from a state of continuum to discontinuum. The risking analysis combines results from other natural fracture prediction tools (e.g. displacement discontinuity method, restoration analyses, curvature analysis, analytical solutions, continuum analysis) to augment FEM-DEM solutions, such as by providing remote and local boundary conditions and identifying potential regions of anticipated damage and fracturing. Natural fractures and damage information is extracted from the modeling results and may be used directly for predictions or used as input into other fracture analysis tools or techniques. The FEM-DEM and risking techniques can be incorporated into a variety of numerical simulation software packages that use a finite-discrete method solver.

A subterranean formation having natural fractures, which is to be subjected to hydraulic fracturing, is first pre-treated with an ultra lightweight (ULW) proppant having an average particle size between from about 12 / 20 to about 40 / 70. The small ULW proppant flows into the natural fractures and packs the fractures. The formation is then subjected to hydraulic fracturing. The pre-treatment serves to enhance the effective propped fracture length of the formation during the hydraulic fracturing by reducing the loss of fluid from the subsequently pumped fracturing fluid. The method is applicable to hydrocarbon bearing formations as well as non-hydrocarbon bearing formations and has particular applicability to coal beds.

The invention relates to the field of oil and natural gas prospecting and exploitation, and provides a method of low-temperature gas-assisted coalbed methane fracturing technology. According to the method, by the aid of ultralow temperature characteristics of liquid nitrogen, cold shock transformation and ice formation are performed on a coalbed, ice blockage is caused to high-permeability channels (such as fractures), and effect of inorganic harmless dissoluble flowback fluid loss additives, even fracturing diverters and the like is achieved, so that the purpose of improving conventional coalbed methane fracturing technology is achieved. The method of the fracturing technology is suitable for primary fracturing of coalbed methane wells non-fractured or with natural fractures existing at the well bottoms, as well as refracturing of coalbed methane wells already fractured but low in productivity.

A method for optimizing hydraulic fracturing simulates the geomechanical interaction between regional stress and natural fractures in a reservoir. An equivalent fracture model is created from data on the natural fracture density, regional stress and geomechanical properties of the reservoir, so that points in the reservoir are assigned a fracture length and fracture orientation. The horizontal differential stress and maximum principal stress direction at points in the reservoir are then estimated by meshless particle-based geomechanical simulation using the equivalent fracture model as an input. The meshless particle-based geomechanical simulator uses the derived initial geomechanical condition to simulate the sequence of hydraulic fracturing and derive the resulting strain and J integral that can be used to estimate the asymmetric half fracture lengths and initial propped permeability needed by hydraulic fracturing design and reservoir simulation software to optimize wellbore and completion stage positions.

The invention discloses a natural fractured reservoir fracturing reformation method. The method includes the steps that 1, linear glue liquid is adopted to conduct stepwise discharge construction on a fractured reservoir to be reformed, and the fractured reservoir natural fracture development degree is obtained in combination with a pumping termination test in the construction process; 2, according to the fractured reservoir natural fracture development degree, smooth ice and propping agents of the first specification are injected into the fractured reservoir to be reformed to conduct first plugging, and a first kind of manual fracture is formed; 3, according to the fractured reservoir natural fracture development degree, particle temporary plugging agents and propping agents of the second specification are injected to the first kind of manual fracture in a slug mode to conduct second sealing, and a second kind of manual fracture is formed; 4, according to the fractured reservoir natural fracture development degree, propping agents of the third specification are injected into the second kind of manual fracture to conduct filling, a third kind of fracture is formed, and natural fractured reservoir fracturing reformation is finished.

The invention discloses a simulating method of the forming process of an unconventional oil and gas reservoir hydraulic fracturing complex fracture net. The method includes the steps of a, reestablishing natural fracture distribution, estimating the properties of natural fractures, obtaining rock mechanical information and stratum stress information of a stratum from log data or a geological model, and obtaining a data file related to the well factory construction process; b, inputting the obtained parameters in an established natural fractured reservoir fracturing model coupling a well cylinder, fractures and the stratum; c, conducting numerical value solving on the model to obtain after-fracturing information such as fracture forms, opening degree distribution and pressure intensity distribution; d, analyzing the fracturing effect through a model calculating result, and making a preparation for numerical value simulation of the later-period production process. The fractured reservoirfracturing numerical value simulating method coupling the well cylinder flowing, the fracture deformation expanding, the multi-state natural fractures and the flowing of fluid in the fractures can quantitatively analyze the form of the unconventional reservoir segmented volume fracture net and is an effectively means for evaluating and optimizing the fracturing scheme.

Methods, systems, and articles of manufacture consistent with the present invention provide for determining the orientation of natural fractures in the Earth resulting from hydraulic fracturing treatment. Data attribute information from a far-field point-source signal profile for a microseismic event is extracted in the time domain. An estimate of the orientation of the natural fracture is calculated in the time domain based on the extracted data attribute information.

The invention discloses a hydraulic fracturing technology for a horizontal well with fractures. The hydraulic fracturing technology comprises the following steps in sequence: (1), according to on-site information, calculating the stress difference values caused by major fractures and adjacent fractures; (2), according to the stress difference values caused by the major fractures and the adjacent fractures, calculating the pressure required when the fracture turns; (3), according to the pressure required when the fracture turns, determining the intensity of temporary plugging agents, and calculating the corresponding construction displacement; (4), according to the design parameters, conducting the segmental multi-cluster fracturing and impulse-type temporary plugging pressurizing technology on a reservoir stratum simultaneously. The hydraulic fracturing technology is mainly based on the horizontal stress difference drop-out values caused by the major fractures and the adjacent fractures, and simultaneously adopts the segmental multi-cluster fracturing and impulse-type temporary plugging pressurizing technology to force the fracture to turn, breaks through the technical bottleneck that the fractures are difficult to form in the stratum with a high stress difference and rudimentary natural fractures, and fills in the blank in the prior art.

The invention belongs to the technical field of artificial rock core preparation, and in particular relates to a preparation method of an artificial rock core of jointing shale. The method comprises the following steps: mixing and stirring cement, quartz sand, clay and gypsum powder; adding a small amount of cereal and scraps of paper into the mixture, adding water into the mixture and stirring uniformly; casting the mixture in a layered manner to form a cement test sample; and coating lubricating oil between every two layers, and drying the cement test sample for molding, thereby obtaining the artificial rock core of the jointing shale. By the preparation method, the cement test sample with certain fracture development, bedding development and brittleness can be obtained, and the mechanical properties of a bedding plane (1), a natural fracture (2), a hydraulic fracture (3) and the like of the jointing shale rock can be simulated relatively accurately, so that shale oil and gas can be developed effectively. According to the preparation method, the used materials are simple, the cost is low, and the operation is simple and convenient.

The invention provides a simulation experiment method of coal seam hydraulic fracture, comprising the following steps of: (a) analyzing natural fracture shape characteristics of a coal rock in a stratum to be simulated, selecting a coal rock material for making a simulation specimen, processing the coal rock material into a hexahedral block according to the natural fracture shape characteristics,and selecting a coating layer carrying out external casting on the block to form the simulation specimen; (b) selecting fluorescent powder as a tracer, and then preparing fracturing fluid; and (c) performing a simulation fracturing experiment with the simulation specimen and the fracturing fluid and acquiring image information of a hydraulic fracture shape and a fracturing fluid swept region after the experiment. In terms of brittle and fragile coal rock with difficulty in processing, after the coating layer is cast by the method disclosed by the invention, the specimen has whole smooth and regular appearance, and the stratification and cutting positions of the coal rock can be well controlled. When the experiment result is acquired, the range of the hydraulic fracture can be clearly displayed by the fluorescent powder, and in particular the micro-fracture that cannot be viewed by the naked eyes can be displayed.

A method for optimizing hydraulic fracturing and refracturing simulates the geomechanical interaction between regional stress and natural fractures in a reservoir. An equivalent fracture model is created from data on the natural fracture density, regional stress and elastic properties of the reservoir, so that points in the reservoir are assigned a fracture length and fracture orientation. The horizontal differential stress and maximum principal stress direction at points in the reservoir are then estimated by meshless particle-based geomechanical simulation using the equivalent fracture model as an input. Regions in the reservoir having low differential stress based on the simulation can then be selected for initial hydraulic fracturing. Regions in the reservoir having high differential stress based on the simulation can then be selected for refracturing.

This invention provides a method for characterizing natural fracture networks or other textural networks in an Earth formation when using microseismic monitoring of a hydraulic fracturing job. The method comprises receiving (120) microseismic data from a hydraulic fracturing event, identifying a data subset (153) comprising components of the microseismic data associated with the one or more hydraulic fractures; and obtaining a remainder dataset (156) of the microseismic data by removing the subset from the microseismic data. One approach for identifying the data subset, after removing high uncertainty microseismic events, is to create a Voronoi diagram of a plurality of cells each associated with one of the microseismic events, determine a density for each cell, create a connectivity matrix of the high density cells and identify event clusters in the connectivity matrix which are aligned with a main growing direction of the hydraulic fracture.

The invention relates to a method for improving the complexity index of a deep shale gas fracture. The method is characterized in that when a fracturing design of the a deep shale gas well is performed, selection and an injection manner of a fracturing fluid, selection of a supporting agent, and the number of perforations are optimized and controlled, and an artificial main fracture can be opened and communicate with a natural fracture as much as possible in an extending process; extension of a single fracture is longer, expansion of the single fracture is wider, and finally the complexity of the deep shale gas fracture can be improved to the greatest extent. The method can be used for deep shale gas reservoirs having the depth of more than 3500 meters and in which the natural fractures containing carbonate minerals are distributed in a reconstruction range of the artificial main fracture, and a certain included angle is formed between the fracturing main fracture and the natural fractures. The method is reasonable in design, is simple in process, is easy to operate, is high in fracturing construction successful rate, can effectively increase the volume of deep shale gas segment fracturing fractures, can remarkably improve the fracturing construction effect, and can acquire more economic benefits.

The invention discloses a calculating method for the size of a fracturing and broken region of a horizontal well for shale. The calculating method comprises following steps of: A, utilizing the theory of crack propagation available to establish a hydraulic fracture extension model during a shale fracturing process; B, utilizing the theory of rock mechanics available to establish a model for stress field variation during a shale fracturing process; C, utilizing the theory of seepage mechanics available to establish a model for pressure field variation during a shale fracturing process; D, utilizing the rock breaking theory available to establish a rule model for natural fractures; E, combining the above four steps to calculate and represent the size of the fracturing and broken region by means of a calculation flow. The calculating method for the size of the fracturing and broken region of the horizontal well for shale has following beneficial effects: time and money spent on calculating the size of the broken region during fracture of the horizontal well for shale are saved so that the valuation of the size of the fracturing and broken region can be extensively prompted and applied.

The invention particularly provides a temporary blocking turnaround fracturing method based on surface modified polyvinyl alcohol fibers. The method comprises the following steps that 1, the surfaces of the water-soluble poly(vinyl alcohol) fibers are modified; 2, fracturing work liquid is prepared; 3, liquid in a shaft is extruded out by and replaced with active water; 4, setting is carried out on a facture packer; 5, prepad fluid is injected, and a major fracture is formed; 6, the water-soluble degradable fiber temporary blocking fracturing liquid is injected into the formed major fracture in a step mode and injected into a stratum to form a new branch fracture; 7, the prepad fluid is injected into the formed new branch fracture, and the length of the fracture is expanded; 8, sand-carrying liquid is injected into the formed new branch fracture in a step mode; 9, the sand-carrying liquid in the shaft is extruded out by and replaced with active water. An old facture or a facture filled with sand is temporarily blocked, the new fractures are made on the original fracture in a certain angle direction, more unused areas of natural fractures and primary fractures are communicated, a new fracture flow leakage system is formed, oil and gas production and the ultimate recovery factor of an oil and gas field are improved, and the aims of restoring the yield of an old well and achieving facture production increase of a new well are achieved.

Fracture- and stress-induced sonic anisotropy is distinguished using a combination of image and sonic logs. Borehole image and sonic logs are acquired via known techniques. Analysis of sonic data from monopole P- and S-waves, monopole Stoneley and cross-dipole shear sonic data in an anisotropic formation are used to estimate at least one compressional and two shear moduli, and the dipole fast shear direction. Fracture analysis of image logs enables determination of fracture types and geometrical properties. Geological and geomechanical analysis from image logs provide a priori discrimination of natural fractures and stress-induced fractures. A forward quantitative model of natural fracture- and stress-induced sonic anisotropy based on the knowledge of fracture properties interpreted from image logs allows the computation of the fast-shear azimuth and the difference in slowness between the fast- and slow-shear. The misfit between predicted and observed sonic measurements (i.e. fast-shear azimuth and slownesses) is then optimized in order to discriminate depth zones with an elastic medium as being influenced by the presence of open natural fractures, closed natural fractures and fractures induced by non-equal principal stress effects.

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 invention provides a shale gas reservoir fracture modeling method based on microseism monitoring data. The method comprises the steps that major fractures of a shale gas reservoir subjected to hydraulic fracturing are modeled to obtain a major fracture model by the adoption of a deterministic modeling method according to the time attribute of microseism event points in the microseism monitoring data in combination with original natural fracture information of the shale gas reservoir; on the basis of the major fracture model and within the effective reconstruction volume range for hydraulic fracturing, constraint conditions of space and geometrical parameters for accompanying fracture simulation in the hydraulic fracturing process are determined according to the density attribute of distribution of the microseism event points in the microseism monitoring data in combination with at least one of the direction attribute, the energy magnitude and the opening degree of the microseism event points, and accompanying fractures of the shale gas reservoir subjected to hydraulic fracturing are modeled by the adoption of a stochastic modeling method to obtain a shale gas reservoir facture basic model. By means of the shale gas reservoir fracture modeling method based on the microseism monitoring data, a complex fracture system of the shale gas reservoir can be depicted meticulously and effectively, and the actual fracture characteristics of the shale gas reservoir subjected to hydraulic fracturing can be reflected.

A subterranean formation having natural fractures, which is to be subjected to hydraulic fracturing, is first pre-treated with an ultra lightweight (ULW) proppant having an average particle size between from about 12 / 20 to about 40 / 70. The small ULW proppant flows into the natural fractures and packs the fractures. The formation is then subjected to hydraulic fracturing. The pre-treatment serves to enhance the effective propped fracture length of the formation during the hydraulic fracturing by reducing the loss of fluid from the subsequently pumped fracturing fluid. The method is applicable to hydrocarbon bearing formations as well as non-hydrocarbon bearing formations and has particular applicability to coal beds.

The invention provides a placing method of a self-simulating lateral-displacement horizontal well of a super-low permeability tight reservoir. The placing method comprises the following specific steps: determining a main force construction layer section; determining the positions of horizontal wells, water injection wells and artificial fractures; determining a well row direction of the horizontal wells; determining a well spacing between the horizontal wells; determining a distance between the rows of the horizontal wells; determining the length of each horizontal well; determining an offset distance of each water injection well; determining a length of each artificial fracture of each water injection well; and injecting water; scattered water injection in the past is changed into linear water injection, and in case of the same water injection amount, a water injection pressure is reduced so that secondary opening of a natural fracture generated in the water injection process can be avoided and a risk of fractured water flooding can be reduced; elastic solution gas drive in a region between the artificial fractures is converted to water drive and a fracture dominant direction of a local region is kept consistent so that early-phase water breakthrough can be avoided and an energy supplementing level can be increased. Row water injection displacement is formed through appropriate fracturing of the directional water injection wells, leading to the advantages that layered water injection can be realized and maximum draw-on in a longitudinal direction can be realized, compared with taking the horizontal wells as the water injection wells.

The invention discloses a method for determining ecological dredging range of water body pollution bottom sediment, comprising steps of: performing space gridding to a water area; setting a sampling point, and obtaining bottom sediment pollution level attribute information of the sampling point; determining the water area requiring dredging after excluding the water area without dredging; processing space interpolation to the bottom sediment attribute information of the water area to cover an unsampled water area with the attribute information, and obtaining the mean value of the single attribute information of the space interpolation in a grid cell, and grading the attribute, and rounding the attribute mean value of the grid cell hierarchically; performing dimensionless standardization treatment of 0-1 numerical values to the hierarchically rounded attribute information, and obtaining the evaluation coefficient of each attribute of the grid cell, summing the evaluation coefficients of all attributes of the grid cell to obtain a comprehensive evaluation value of the grid cell; classifying the comprehensive evaluation values of all grid cells by a natural breaking method of geographic information software and determining the recommended dredging area as the ecological dredging range with high comprehensive evaluation value.

A method for predicting localized damage and naturally occurring fractures in a subsurface region is provided. This invention uses a hybrid FEM-DEM (i.e. finite-discrete element) framework combined with a fracture risking analysis and fracture initiation and propagation criteria, to model the transition of rock from a state of continuum to discontinuum. The risking analysis combines results from other natural fracture prediction tools (e.g. displacement discontinuity method, restoration analysis, curvature analysis, analytical solutions, continuum analysis) to augment FEM-DEM solutions, such as by providing remote and local boundary conditions and identifying potential regions of anticipated damage and fracturing. Natural fractures and damage information is extracted from the modeling results and may be used directly for predictions or used as input into other fracture analysis tools or techniques. The FEM-DEM and risking techniques can be incorporated into a variety of numerical simulation software packages that use a finite-discrete method solver.

The invention provides a staged fracturing or synchronous fracturing simulation experiment method for a shale horizontal well. The method comprises the following steps: (a) the natural fracture morphological characteristics of shale in a stratum to be simulated are analyzed; a shale outcrop material for producing a simulation test piece is selected, and the shale material is machined to a cube rock mass according to the shale settled layer characteristics; and the surface of the mass is brushed with resin adhesive for sealing; (b) a through hole is drilled in the middle of the test piece; and when the synchronous fracturing of the horizontal well is simulated, two equal holes are drilled; (c) silent crushing agent slurry filling sections are added in the drill holes; and the needed number of fracturing sections is produced by partition pieces; and (d) the simulation fracturing experiment is performed by using the simulation test piece; and fracture morphology image information in a rock core is obtained after the experiment. For brittle shale with natural fracture development, the method is easy to realize the experimental simulation of staged fracturing or synchronous fracturing of the horizontal well. Meanwhile, the high-energy CT scanning is performed for the test piece through a linear accelerator nondestructive testing system to realize precise observation of a shale fracturing net. The experiment method can be applied to the research on propagation rules of the shale fracturing net under the effect of matrix pressure transfer.

The invention discloses a volume alternating fracturing method of a horizontal well in an experimental shale reservoir. The method comprises the following steps: collecting the stratum parameter, the natural fracture parameter and the hydraulic fracture basic parameter of a reservoir; establishing stretching, shearing and pass through failure criterions of a natural fracture when a hydraulic fracture and the natural fracture are interacted, and quantitatively analyzing the influence on the natural fracture failure by a horizontal principal stress difference; establishing a hydraulic fracture induced stress calculation model, and computing the influence on the induced stress of a middle perforation cluster fracture elongated area by gaps among different perforation cluster fractures and fracture extended lengths; optimally selecting a shale reservoir horizontal well volume fracturing perforation cluster gap and perforation cluster extended lengths at the two ends, so as to promote a middle perforation cluster hydraulic fracturing fracture to be extended and interactively produce stretching, shearing and pass through failure modes with the natural fracture at the same time to form a complex fracture. According to the method, induced stress field produced through the extension of the hydraulic fracture, perforation gaps within the same fracturing section and the extended fracture lengths are organically combined, and the horizontal well volume fracturing technology is properly perfected.

The invention discloses a cluster interval optimizing method for segmental multi-cluster fracturing of a horizontal well of a low-permeability oil and gas reservoir. The cluster interval optimizing method for segmental multi-cluster fracturing of the horizontal well of the low-permeability oil and gas reservoir sequentially comprises the following steps that (1) the induced stress generated by hydraulic fractures in a stratum is calculated; (2) the formation pore pressure after fracturing liquid is leaked off is calculated; (3) formation pore elastic stress after the fracturing liquid is leaked off is calculated; (4) the three induced stress fields and the original ground stress field are superposed, so that a new ground stress field is obtained; (5) facture network waves and the region area are calculated; and (6) a relation curve chart of the fracture cluster interval, the fracture network waves and the region area is drawn with the cluster interval being used as x-coordinates and the fracture network waves and region areas being used as y-coordinates, and the optimal cluster interval is determined. According to the cluster interval optimizing method for segmental multi-cluster fracturing of the horizontal well of the low-permeability oil and gas reservoir, the interference effect of the hydraulic fractures on the original ground stress field is considered, the expanding and shear fracturing behaviors of natural fractures under a complex ground stress field condition are also considered, and the novel cluster interval optimizing method is formed with the optimization goal of obtaining the maximum fracture network wave and the maximum region area; and the novel cluster interval optimizing method is more objective, accurate and practical.