Study On Carbonate Rock Mechanical Parameters Testing And Crack Propagation In Area G

Carbonate reservoirs are an important reservoir type for onshore oil and gas exploration in China,and their storage and permeability space is different from ordinary sandstone.The main storage spaces of carbonate reservoirs are karst caves and fractures,and fracture-cavity carbonate reservoirs are one of the most representative.Therefore,the study of fracture-cavity carbonate reservoirs is particularly important from the perspective of the entire oil and gas reservoir development.In this paper,the carbonate rock samples in the G area are systematically simulated by rock mechanics parameters,and combined with the rock mechanical characteristics and fracture propagation mechanism of the sample,the fracture propagation of the carbonate reservoir is analyzed,and the numerical simulation is used to Its further analysis.This article is divided into two parts: indoor physical model experiment and numerical simulation research,of which physical simulation is the main part.In this paper,rock mechanics testing experiments are carried out on the carbonate reservoir cores in the G area.The experiments include conventional triaxial tests,in-situ stress magnitude and direction tests,rock fracture toughness tests,rock sample nuclear magnetic resonance tests,and full-diameter rock sample physical simulation experiments.Finally,the rock mechanical parameters such as fracture toughness,Young's modulus,rock brittleness index,Poisson's ratio,Biot's coefficient,the size and direction of the maximum and minimum horizontal principal stress are obtained,and then through the full-diameter rock sample physical simulation experiment,the hydraulic pressure Physical simulation of the crack initiation and propagation process is carried out to simulate the crack shape after hydraulic fracturing,and the initiation and extension laws are studied.The numerical simulation part is based on the ABAQUS software to simulate the expansion and extension of carbonate hydraulic fracturing fractures,in which the fractures use cohesive viscous units to study the turning of the fracture due to the difference in horizontal stress and the turning of the natural fracture.The problem is to discuss the change of fracture network shape caused by fracturing fluid viscosity and construction displacement.Simulated changes in Young's modulus,Poisson's ratio,compressive strength and other parameters lead to changes in crack morphology and direction,to verify the correctness of physical simulation experiments.The results of laboratory physical model experiments and numerical simulation analysis further clarified the mechanism of hydraulic fracturing in fractured-cavity carbonate reservoirs,evaluated the initiation characteristics of hydraulic fracturing fractures in the G area,and proposed that the fracture patterns at high displacements have The trend of transition to complex fractures,it is recommended to use volumetric acid fracturing with large displacement and large fluid volume for reservoir reconstruction.Reliable suggestions are provided to the site on the technical theory,guidance technology optimization and scheme optimization of enhanced oil recovery in fracture-cavity reservoirs.