Abstract: A double-layer coiled tubing double-gradient drilling system, on the basis of conventional drilling equipment, includes a double-layer coiled tubing system, separating fluid, a downhole lifting pump system, throttling control systems and a data monitoring system. Power fluid enters an annular space of the tubing through an adapter, passes through a downhole lifting pump, enters an inner pipe through a bridge channel, and enters the bottom hole through the drill bit. Return fluid enters an annular channel of the tubing through a recovery hole, then enters the inner pipe through the bridge channel and enters the lifting pump, and then enters a solid control system through the adapter and the control systems in sequence. Gradient control of the bottom hole pressure is realized through monitoring of the separating fluid and control of the drilling pump unit and throttling control systems. The problem of narrow safe drilling density window is solved.

Abstract: An experimental method for determining flow patterns in vertical wellbore of gas wells at high-pressure conditions, which falls within the technical field of deliquification for gas reservoirs. The method comprises: collecting target block parameters; Developing physical simulation experiment to measure the liquid holdup of vertical wellbore; Constructing similarity dimension number to characterize gas density and change with liquid holdup to represent flow similarity of different gas velocities at different pressures; Utilizing equal liquid holdup to represent flow similarity, fitting similarity dimension coefficient, normalizing flow under different pressure conditions to same similarity dimension number, realizing coincidence of change cure of liquid holdup of normal pressure and medium pressure with similarity dimension number.

Abstract: An integrated wellhead device for filtering injected and produced gases is provided. The wellhead device comprises a horizontal tank body that is internally provided with an injected gas filtering system and a produced gas filtering system. The injected gas filtering system is internally provided with an oxygen removal chamber. A gas inlet of the injected gas filtering system is connected with an injected high-pressure gas source, and a gas outlet of the injected gas filtering system is connected with a gas injection well casing of Christmas tree. The produced gas filtering system is internally equipped with an oxygen removal chamber, a sulfur removal chamber and a carbon dioxide removal chamber. A gas inlet of the produced gas filtering system is connected with a gas production tubing of the Christmas tree, and a gas outlet of the produced gas filtering system is connected with a produced gas transmission pipe.

Abstract: The invention discloses an organic-inorganic nanocomposite gel sealing agent and oil-based drilling fluid. The sealing agent used for the oil-based drilling fluid is organic-inorganic nanocomposite gel, and the synthetic raw materials of the organic-inorganic nanocomposite gel includes molybdenum disulfide, 2-ethyl acrylic acid, N, N-dimethylacrylamide and N,N-methylene bisacrylamide; the drilling fluid includes the organic-inorganic nanocomposite gel provided by the invention.

Abstract: The present invention belongs to the technical field of oil and gas field development, and discloses a method for calculating a single-well controlled reserve of a low-permeability/tight gas reservoir and analyzing residual gas thereof. The method includes: calculating a reserve controlled by each gas well in a block by using a gas reservoir dynamic reserve calculation method; establishing a new reserve calculation formula for solution and comparative analysis by an example; and quantitatively analyzing an effect of a startup pressure gradient and a stress sensitivity on a calculation result of the single-well controlled reserve, wherein the analysis of the factors affecting reserve calculation shows that, when the startup pressure gradient reaches 0.02 MPa/m, the calculated reserve is significantly reduced compared with a conventional method, but when the startup pressure gradient is greater than 0.1 MPa/m, the effect gradually stabilizes.

Abstract: The invention discloses a digital imaging technology-based method for calculating relative permeability of tight core, comprising the following steps: step S1: preparing a small column sample of tight core satisfying resolution requirements; step S2: scanning the sample by MicroCT-400 and establish a digital core; step S3: performing statistical analysis on parameters reflecting the characteristics of rock pore structure and shape according to the digital core; step S4: calculating tortuosity fractal dimension DT and porosity fractal dimension Df by a 3D image fractal box dimension algorithm; step S5: performing statistical analysis on maximum pore equivalent diameter ?max and minimum pore equivalent diameter ?min by a label. The present invention solves the problems of time consumption of experiment, instrument accuracy, incapability of repeated calculation simulations and resource waste by repeated physical experiment.

Abstract: The disclosure discloses a solid fluidization tubular separator for marine natural gas hydrate, which includes a first separator and a second separator, wherein the first separator includes the first separation sleeve, the power liquid pipe, the swirl baffle, the recovery mechanism and the sand discharge mechanism. After the hydrate is sucked into the first separation sleeve to generate a circumferential velocity, so that the mud and sand with high density are separated to the pipe wall of the first separation sleeve, and the mud and sand separated to the pipe wall are settled down from the gap between the swirl baffle and the pipe wall along the pipe wall. The hydrate swirl flows into the recovery mechanism, and then leaves the first separation sleeve and enters the second separator, so as to realize the separation of mud and sand and natural gas hydrate.

Abstract: The present invention discloses a method for determining the stimulated reservoir volume of horizontal wells by coupling reservoir flow, comprising the following steps: establishing a reservoir grid based on the reservoir geological model of the target well and adding an initial fracture unit; calculating the stress intensity factor at the fracture tip, judging the fracture initiation and determining the total number of fracture units; calculating the fluid pressure of fracture units, the pore pressure distribution and water saturation distribution of the reservoir matrix and micro-fractures during hydraulic fracturing; working out the stimulated reservoir volume of the horizontal well according to the fracture parameters, pressure distribution and water saturation distribution in shale reservoirs. The present invention can simulate fracture propagation, fracturing fluid leak-off and reservoir fluid flow in the whole fracturing process, determine the stimulated reservoir volume of horizontal wells.

Abstract: A fully electrically controlled intelligent subsurface safety valve is provided, including an upper joint, a lower joint, a magnetic switch, an upper electromagnetic suction module, a central flow pipe, a magnetic piston ring, a lower electromagnetic suction module, a rebound flap valve mechanism, a displacement sensor, a temperature and pressure sensor, a flow sensor, and a power communication composite cable connector. With the magnetic assisted reset of the two electromagnetic suction modules, the safety valve closes more quickly in emergency situations, improving the reliability of the safety valve. By using a magnetic excitation switch, the safety valve can be quickly opened and closed, and the open or close state can be maintained independently, saving energy consumption in the control system. The present disclosure can better meet the needs of onshore and offshore oil and gas production operations and gas storage operations.

Abstract: A sealing integrity evaluation device for high-temperature and high-pressure casing-cement ring-formation and a method thereof are provided. the device includes: a high-temperature autoclave, a temperature and pressure control system, and a casing-cement-formation combination; wherein the autoclave realizes alternating temperature and pressure during the experiment; the control system monitors, controls and records the temperature and pressure data; the combination simulates a full size or a compact size casing-cement-formation of a well.

Abstract: A simulation device and a simulation method for gas reservoir exploitation are provided. The simulation device includes a gas-liquid supply system, a simulation system, a metering system, pipes for interconnecting each system, and switches, wherein: the gas-liquid supply system includes a gas supply system and a liquid supply system; the metering system is for metering gas and/or liquid produced after the simulation system; the simulation system includes core models having at least one of micro-fractures with an aperture smaller than 1 ?m, map-fractures with an aperture between 10-20 ?m, and large-fractures with an aperture between 100-5000 ?m. The present invention is able to accurately simulate water invasion and water-controlled gas production processes of different fractured gas reservoirs under different bottom water energies.

Abstract: The invention discloses a full wellbore pressure calculation method, device and computer-readable storage medium for fracturing horizontal wells, includes steps: collect basic parameters, establish fully implicit numerical model of formation flow; solve the full implicit numerical model under an inner boundary condition of a constant gas production rate; calculate wellbore pressure change of each fracturing section of horizontal well; calculate the bottom-hole pressure of each fracture initiation point; repeat steps until the variables converge, the bottom-hole flow pressure and the bottom-hole pressure at each fracture initiation point are obtained at this time step; the wellbore pressure and wellhead casing pressure are calculated at this time step.

Abstract: A pressure pulse communication system and method during gas drilling are provided. The system includes a downhole solenoid valve module and a sensor module, where the downhole solenoid valve module includes a valve body, a gas inlet, a piston micro-hole, a moving piston, a piston return spring, a piston cylinder, a gas outlet, a piston pressure relief hole, a solenoid valve spring, a solenoid valve, a battery, a pressure balancer, and a rubber seal. The pressure pulse communication system and method generate pressure pulses by changing the internal pressure of a drill pipe, such that a surface pressure sensor continuously receives the pressure pulses, thereby achieving the purpose of acquiring downhole temperature, pressure, and well inclination angle data.

Abstract: The application discloses a reversible plugging-type device for preventing seepage from a side wall of an irregular sample (14), comprising a sleeve (15) with both ends open, a primary lantern ring (4), a secondary lantern ring (5), a tertiary lantern ring (26) and a rotation shaft (1) arranged in a barrel (2), a lower end surface of the barrel (2) is provided with an annular floating plate (17), the primary lantern ring (4), the secondary lantern ring (5), and the tertiary lantern ring (26) are hollow, first phase liquid pipe (7) is arranged on a lower end surface of the primary lantern ring (4), second phase liquid pipe (8) is arranged on a lower end surface of the secondary lantern ring (5), the first phase liquid pipe (7) and the second phase liquid pipe (8) extend downward toward a mixing pipe (10). The floating plate (17) has the mixing pipe (10), which runs through the floating plate (17) and has a discharging pipe (22) provided with a discharge port (23).

Abstract: A method for coupling hydraulic fracture network extension and production performance of a horizontal well in an unconventional oil and gas reservoir includes: establishing a complex hydraulic fracture network model of a fractured horizontal well in an unconventional oil and gas reservoir based on a fracture extension theory; constructing three-dimensional three-phase mathematical models of seepage for the fractured horizontal well based on an embedded discrete fracture model; and constructing a fully implicit numerical calculation model by a finite difference method through three-dimensional orthogonal grids, and solving iteratively, thereby accurately predicting a production performance characteristic of the fractured horizontal well in the unconventional oil and gas reservoir.

Abstract: A tight oil reservoir CO2 flooding multi-scale channeling control system and a preparation method, including nanoscale CO2 responsive worm-like micellar systems and micron-scale CO2 responsive dispersion gel, are provided. The nanoscale CO2 responsive worm-like micelle system is prepared by CO2 reactive monomers and organic anti-ion monomers stirred in water. The micron-scale CO2 responsive dispersion gel is made of acrylamide, a responsive monomer, a silane coupling agent modified hydroxylated multi-walled carbon nanotubes as raw materials, cross-linked in water.

Abstract: Disclosed are a high-temperature-resistant tertiary amine-grafted silica nano-plugging agent and water-based drilling fluids, relating to oil-gas field drilling. The nano-plugging agent is prepared from a hydrazine compound, a diallyl compound, an enamine compound, silica particle, and an amino-containing silane coupling agent by stepwise reaction. The nano-plugging agent has a grain size of 58-280 nm.

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 a method for evaluating fracture connectivity and optimizing fracture parameters based on complex network theory, comprising the following steps: obtaining natural fracture distribution laws and characteristic parameters of the formation based on previous knowledge of natural fractures in the formation and statistical analysis of fractures in the core, and establishing a discrete fracture network model of natural fractures based on the previous step; setting up hydraulic fractures, determining intersection relations in the fracture network and coordinates of intersection points of fractures: converting the actual fracture network into a complex network dual topology diagram based on complex network theory, and calculating evaluative indexes of the complex network to realize the evaluation of fracture network connectivity; changing the hydraulic fracture parameters to get the evaluation indexes of different hydraulic fracture schemes.