Abstract: A temperature-resistant and salt-tolerant in-situ plugging-enhanced gel composition, a gel, and their preparation method and application are provided. The gel composition includes a first monomer, a second monomer, a first crosslinking agent, a second crosslinking agent, an initiator, an enhancer, and water; optionally, the composition further includes a third monomer. The gel can undergo re-crosslinking under stimulation by high temperature and CO2-acidic conditions to form the bulk gel, thereby avoiding issues associated with in-situ gel systems such as crosslinking uncertainty, chromatographic separation, and susceptibility to reservoir damage, while simultaneously achieving enhanced plugging capability under in-situ reservoir conditions.

Abstract: The present disclosure presents a device and method for calculating a change in CO2 storage capacity before and after drying, wherein the method comprises the following steps: S1: acquire a target stratum core and prepare a formation water sample and a gaseous CO2 sample; S2: measure the content of the saturated condensate water of the gaseous CO2 sample under a target formation condition; S3: saturate formation water for the target stratum core; S4: perform displacement experiments until a water saturation of a core at the target stratum reaches saturation of irreducible water in an actual stratum, and record a core porosity ?0 at this time; S5: continue the displacement experiment until all the formation water in the core of the target stratum has evaporated, and record the core porosity ?1 at this time; S6: calculate a drying radius of reservoir and the change of CO2 storage capacity after reservoir drying.

Abstract: Disclosed is a method for evaluating the underground hydrogen storage (UHS) capacity in porous media of depleted gas reservoirs using CO2 as cushion gas, including the following steps: S1: obtaining physical parameters required for UHS capacity evaluation based on geological and production data of the target depleted gas reservoir; S2: calculating the cap-rock breakthrough pressure and fault-slip pressure of the UHS based on the cap and fault properties of the target depleted gas reservoir to further estimate the highest operating pressure of the UHS; S3: developing the H2—CO2—CH4 multi-component material balance equation in underground porous media by considering the dissolution of three components in formation water; S4: substituting the parameters obtained from S1 and S2 into the multi-component material balance equation to calculate the proportion of different gas components in the pore space to finally determine the UHS capacity of the target depleted gas reservoir.

Abstract: Disclosed is a method for evaluating the underground hydrogen storage (UHS) capacity in porous media of depleted gas reservoirs using CO2 as cushion gas, including the following steps: S1: obtaining physical parameters required for UHS capacity evaluation based on geological and production data of the target depleted gas reservoir; S2: calculating the cap-rock breakthrough pressure and fault-slip pressure of the UHS based on the cap and fault properties of the target depleted gas reservoir to further estimate the highest operating pressure of the UHS; S3: developing the H2—CO2—CH4 multi-component material balance equation in underground porous media by considering the dissolution of three components in formation water; S4: substituting the parameters obtained from S1 and S2 into the multi-component material balance equation to calculate the proportion of different gas components in the pore space to finally determine the UHS capacity of the target depleted gas reservoir.

Abstract: Methods and systems for testing retrograde condensation damage in a near well zone of a condensate gas reservoir with a high condensate content are provided. The device comprises a long rock core holder, a first two-way valve, a second two-way valve, a first single-way valve, a second single-way valve, a third single-way valve, a fourth single-way valve, a first three-way valve, a second three-way valve, a third three-way valve, a confining pressure pump, a confining pressure gauge, a vacuum pump, a high-pressure high-precision displacement pump, a first intermediate container, an outlet pressure gauge, a displacement pump, a back pressure valve, a gas meter, a second intermediate container, an inlet pressure gauge, a test tube, a constant temperature oven, a gas flowmeter, a gas chromatograph, a six-way valve, a sample preparation device, and a thermostatic chamber.