Abstract: The present disclosure relates to a method for evaluating a temporary plugging effect of fracturing in a low-permeability oil-gas reservoir based on monitoring pressure. The method comprises: calculating a wellbore friction resistance along a way from a wellhead to a target fracturing segment; calculating, based on a wellhead pressure monitored at the wellhead in real time, a wellbore pressure at the target fracturing segment; calculating a fluid pressure at a crack opening of each perforation cluster; calculating a perforation friction resistance coefficient of each perforation cluster; calculating a fracturing fluid instantaneous displacement of each perforation cluster; calculating, based on the fracturing fluid instantaneous displacement of each perforation cluster, a variation coefficient of a fracturing fluid displacement distribution after a fracturing construction is completed; and evaluating the temporary plugging effect of fracturing based on the variation coefficient.

Abstract: Disclosed are a CO2 gas-soluble silicon nanofluid and a preparation method therefor. The method includes: taking nano-silica and grafting a silane coupling agent to obtain modified nano-silica; taking methylsiloxane, fluorosilicone, aminosiloxane and an end-capping agent, and performing polymerization under the action of a catalyst to obtain a functionalized network siloxane; and taking the modified nano-silica and the functionalized network siloxane, uniformly mixing, then heating for a Michael addition reaction, and obtaining the gas-soluble silicon nanofluid after the reaction is completed. The gas-soluble silicon nanofluid microscopically forms a network structure with modified nano-silica as a cross-linking point and polysiloxane as a chain; macroscopically, the effect of viscosity increase of the supercritical carbon dioxide is significant, and the dissolving pressure is low. The interfacial tension and the miscibility pressure between the crude oil and CO2 are significantly reduced.

Abstract: The present invention discloses a supercritical CO2 thickener for shale gas reservoir based on hollow mesoporous silica nanoparticles and a preparation method thereof, and relates to the technical field of oil and gas field development. The preparation method of the thickener includes: reacting a monomer consisting of fluoroacrylate, styrene and vinyl acetate in a molar ratio of 3-5:1-2:1-2 with 2%-5% of a total weight of hollow mesoporous silica nanoparticles with carbon-carbon double bonds under the action of an initiator to obtain the thickener. The preparation method of the present invention does not involve the addition of organic solvents during the reaction process and thus does not cause harm to the human body. The thickener of the present invention has good CO2 viscosity-increasing effect and good sand carrying performance, and can effectively improve the fracturing effect.

Abstract: The embodiments of the present disclosure provide a method for diagnosing control effectiveness of a fracture height in hydraulic fracturing by combining monitoring a pressure signal, comprising: obtaining engineering data and geological data; calculating a fracture slit fluid pressure, a double-logarithmic slope of the fracture slit fluid pressure, and a bedding fracture pressure; updating a growth time of the fracture height and a reference pressure based on the fracture height in hydraulic fracturing; based on determining whether a fracturing construction operation ends, updating the cumulative fracturing time or calculating a ratio of the growth time of the fracture height to the total time of hydraulic fracturing.

Abstract: The present invention discloses a double-crosslinked thermal phase transition gel temporary plugging agent and an application thereof, and relates to the technical field of oil and gas field development. The gel temporary plugging agent comprises the following components in percentage by weight: 5.8-18.3% of acrylic acid, 2.8-6.5% of 2-acrylamide-2-methylpropanesulfonic acid, 2.8-7.0% of hydroxyethyl acrylate, 0.2-1.0% of a degradable crosslinking agent, 0.4-1.2% of borax or boric acid, 0.2-0.8% of a high-temperature initiator, 2.6-4.5% of palygorskite attapulgite, 1.5-3.1% of a urea-formaldehyde resin, and the balance of water, wherein the gel temporary plugging agent is formed by underground gelation. The gel temporary plugging agent is applied to oil and gas reservoirs with a temperature of 100-150° C., can automatically be subjected to gelation and degradation, and has a low filtration loss before gelation.

Abstract: A displacement system designed for robust heterogeneous oil reservoirs and its application within the oil exploitation field. System comprises a polymer-enhanced foam plugging agent and an active polymer flooding agent. Plugging agent consists of 0.12% bio-polysaccharide polymer diutan gum foam stabilizer and 0.4% ?-olefin sulfonate foaming agent by mass. The active polymer flooding agent is formulated through free radical polymerization, with components comprising a total monomer concentration of 27.5%, wherein monomer A to monomer B ratio is 7.5:2.5, monomer C constitutes 5.5% of the total monomer concentration, and water comprises the remaining. Monomer A is acrylamide, monomer B is 2-acrylamide-2-methyl propane sulfonic acid, and monomer C is a quaternary ammonium salt type active monomer. Demonstrated through parallel core displacement experiments, this displacement system exhibits effective displacement in heterogeneous oil reservoirs with a permeability gradation of 30 at 65° C.

Abstract: The present invention discloses a CO2 responsive core-shell multi-stage swelling microsphere and a preparation method thereof. The preparation method comprises the following steps: adding a styrene monomer into a sodium dodecyl sulfate solution for emulsion polymerization to obtain a spherical polystyrene solution, taking azobisisobutyronitrile and ethylene glycol for Pinner reaction to obtain an azo compound with hydroxyl functional groups at two ends, taking the azo compound with the hydroxyl functional groups at two ends as a raw material for Schotten-Baumann reaction with methacryloyl chloride to obtain BPAB, adding the BPAB into the spherical polystyrene solution to prepare an active polystyrene core solution, and dissolving the active polystyrene core solution, acrylamide, a CO2 responsive monomer, a CO2 responsive cross-linking agent and a stable cross-linking agent into water to obtain a target product.

Abstract: The present invention provides an asphaltene dispersion stabilizer and a preparation method therefor, and relates to the technical field of oilfield additives. The asphaltene dispersion stabilizer is prepared by the following method: taking iminodisuccinic acid or salt thereof, and performing Michael addition reaction on the iminodisuccinic acid or the salt thereof and unsaturated sulfonate to prepare a first intermediate; taking the first intermediate, and performing amidation reaction on the first intermediate and a first monomer under the action of a catalyst to obtain a second intermediate; and preparing a dendrimer by taking the second intermediate as a core and taking a second monomer and a third monomer as raw materials, wherein the dendrimer is the asphaltene dispersion stabilizer, and the generation number of the dendrimer is 0.5 generations, 1.5 generations or 2.5 generations. The asphaltene dispersion stabilizer of the present invention has a good dispersion stabilization effect on asphaltene.

Abstract: The present invention discloses a method for realizing uniform stimulation for the oil and gas well by low-cost multi-stage fracturing, comprising the following steps: first calculate and predict the inlet widths of the fracture created in the planned hydraulic fracturing; then design the plugging scheme for blocking the fracture inlet after each fracturing treatment; the selected plugging particles are composed of filling particles and skeleton particles, with designed plugging scheme; after complete the design of plugging scheme, perform the fracturing treatment to create hydraulic fracturing in the reservoir; skeleton particles and filling particles are added into the fractures successively according to plan. The present invention provides a multi-stage single-cluster fracturing method, with the advantages of controllable fracture sizes and low cost. The present invention can realize a good uniformity of stimulation for the oil and gas wells.

Abstract: The present invention discloses a method for realizing uniform stimulation for the oil and gas well by low-cost multi-stage fracturing, comprising the following steps: first calculate and predict the inlet widths of the fracture created in the planned hydraulic fracturing; then design the plugging scheme for blocking the fracture inlet after each fracturing treatment; the selected plugging particles are composed of filling particles and skeleton particles, with designed plugging scheme; after complete the design of plugging scheme, perform the fracturing treatment to create hydraulic fracturing in the reservoir; skeleton particles and filling particles are added into the fractures successively according to plan. The present invention provides a multi-stage single-cluster fracturing method, with the advantages of controllable fracture sizes and low cost. The present invention can realize a good uniformity of stimulation for the oil and gas wells.

Abstract: The present invention discloses an optimized design method for a temporary blocking agent to promote uniform expansion of fractures produced by fracturing in horizontal wells, which comprises the following steps: calculating a particle size and a volume range of a candidate temporary blocking agent in an applicable target area; establishing a hydraulic fracture expansion calculation model with complete fluid-solid coupling; calculating an optimal average particle size required for effective temporary blocking; determining the particle size distribution of the temporarily blocked particles according to the optimal average particle size; calculating the particle volume of the temporary blocking agent required for effective temporary blocking; and predicting and evaluating a fracturing effect after the preferred temporary blocking design is adopted in the target area.

Abstract: A crushing system for large-size natural gas hydrate rock samples, which mainly includes a crushing and stirring control subsystem, crushing and stirring execution subsystem and hydrate preparation subsystem. Full automatic control to parameter acquisition and experimental process is achieved by utilizing modern automation technology, including the function of automatically crushing the large-size natural gas hydrate rock samples and also monitoring, collecting and storing the drilling pressure, the torque and the internal furnace pressure and temperature parameters during the crushing process in real time, to provide reliable guarantee for the follow-up researches on crushing mechanism, crushing efficiency, drilling parameter optimization, rock crushing ability evaluation of a crushing tool and the like of the large-size natural gas hydrate rock samples and necessary experimental verification means for optimization of on-site exploiting construction conditions of natural gas hydrate.

Abstract: The present invention discloses a gas flow rate analysis and prediction method for wellhead choke of gas well based on Gaussian process regression, comprising the following steps of Step 1) acquiring basic data of the wellhead choke on site, Step 2) selecting a kernel function, Step 3) calculating a covariance matrix, Step 4) testing the Gaussian process regression model with the test data sample to calculate a prediction deviation, Step 5) selecting different kernel functions, repeating Steps 2-4, comparing prediction deviations of the different kernel functions, and Step 6) analyzing and predicting the gas flow rate of the wellhead choke of the gas well to be tested. According to the method, the data of the wellhead choke of the gas well can be processed effectively, and the gas flow rate can be predicted accurately under the condition that there is gas-liquid flow rate in the wellhead choke.

Abstract: A high-temperature and high-pressure microscopic visual flowing device and an experimental method are provided by the present disclosure, comprising a seepage simulation system, a micro-displacement and metering system connected to the seepage simulation system, and an image acquisition and analysis system; the seepage simulation system consists of a visual high-temperature and high-pressure kettle, a microscopic core model placed in the visual high-temperature and high-pressure kettle, and glass carriers arranged above and below the microscopic core model; the glass carriers are provided with sealing rubber sleeves, and the visual high-temperature and high-pressure kettle is provided with an annular heating jacket; an outlet of the microscopic core model is provided with a microflow channel which is connected to the micro-displacement and metering system through a pipe, effectively reducing the metering error caused by the dead volume of the pipe.

Abstract: An emulsifier with high temperature resistance, low viscosity and low corrosiveness, and an emulsified acid system comprising the same. The emulsifier includes a viscoelastic surfactant, which is prepared by a quaterization of fatty acid acyl propyl dimethylamine and a halogenated compound; by a quaterization of a long-chain halogenated hydrocarbon and a tertiary amine compound; or by a reaction of the fatty acid acyl propyl dimethylamine with a linking group synthesized by epichlorohydrin and an alkylamine compound.

Abstract: A high-temperature and high-pressure microscopic visual flowing device and an experimental method are provided by the present disclosure, comprising a seepage simulation system, a micro-displacement and metering system connected to the seepage simulation system, and an image acquisition and analysis system; the seepage simulation system consists of a visual high-temperature and high-pressure kettle, a microscopic core model placed in the visual high-temperature and high-pressure kettle, and glass carriers arranged above and below the microscopic core model; the glass carriers are provided with sealing rubber sleeves, and the visual high-temperature and high-pressure kettle is provided with an annular heating jacket; an outlet of the microscopic core model is provided with a microflow channel which is connected to the micro-displacement and metering system through a pipe, effectively reducing the metering error caused by the dead volume of the pipe.

Abstract: A natural gas hydrate solid-state fluidization mining method and system under an underbalanced positive circulation condition, used for performing solid-state fluidization mining on a non-rock-forming weak-cementation natural gas hydrate layer in the ocean. Equipment includes a ground equipment system and an underwater equipment system. The construction procedure has an earlier-stage construction process, underbalanced hydrate solid-state fluidization mining construction process and silt backfilling process. Natural gas hydrates in the seafloor are mined through an underbalanced positive circulation method.

Abstract: The invention discloses a method for simulating the discontinuity of the hydraulic fracture wall in fractured reservoirs, comprising the following steps: establish a physical model of the natural fracture; establish a hydraulic fracture propagation calculation equation; establish a natural fracture failure model, calculate the natural fracture aperture, and then calculate the natural fracture permeability, and finally convert the natural fracture permeability into the permeability of the porous medium; couple the hydraulic fracture propagation calculation equation with the permeability of the porous medium through the fracture propagation criterion and the fluid loss to obtain a pore elastic model of the coupled natural fracture considering the influence of the natural fracture; work out the stress and displacement distribution of the hydraulic fracture wall with the pore elastic model of the coupled natural fracture, and analyze the offset and discontinuity of the hydraulic fracture wall according to the dis

Abstract: An optimization method for high-efficiently placing proppants in a hydraulic fracturing treatment includes steps of: (1) constructing a rock deformation governing equation during a fracturing process, and constructing a material balance equation of flowing of fracturing fluid and transport of the proppant; (2) constructing a model for representing a pumped volume fraction of the proppant; (3) calculating with given parameters, and obtaining corresponding fracture geometric size and volumetric concentration distribution of the proppant; (4) calculating a placement efficiency of the proppant for each set of parameters; (5) calculating an average placement efficiency of the proppant under different parameters; (6) selecting optimized parameters; (7) substituting the optimized parameters into the models constructed in the steps (1) and (2), calculating the placement efficiency of the proppant as step (4), and verifying whether the placement efficiency is maximum, which means the optimized parameters are optimal.

Abstract: An emulsifier with high temperature resistance, low viscosity and low corrosiveness, and an emulsified acid system comprising the same. The emulsifier includes a viscoelastic surfactant, which is prepared by a quaterization of fatty acid acyl propyl dimethylamine and a halogenated compound; by a quaterization of a long-chain halogenated hydrocarbon and a tertiary amine compound; or by a reaction of the fatty acid acyl propyl dimethylamine with a linking group synthesized by epichlorohydrin and an alkylamine compound.