Fracture Evaluation Of Tight Sandstone In L Area

With the development of oil and gas exploration,the proportion of tight sandstone gas in China's natural gas production is increasing.In tight sandstone oil and gas exploitation,how to obtain economical oil and gas resources from tight reservoirs with low porosity and low permeability is an urgent problem to be solved.In order to obtain oil and gas industry exploitation and obtain economic benefits,it is necessary to carry out fracturing reconstruction of the reservoir section.Hydraulic fracturing is an important measure for the production enhancement of tight sandstone oil and gas,and the more complex the fracture network formed after fracturing,the better the fracturing effect.The tight sandstone gas in the Upper Paleozoic of the Ordos Basin is widely distributed.The evaluation of fracturing performance in tight sandstone reservoirs is of great significance to the development of tight sandstones.The research on fracturing is mainly focused on the assessment of the brittleness index of tight sandstone reservoirs.Due to the strong heterogeneity of tight sandstones,the assessment of brittleness index is too unilateral,and it is impossible to fully characterize the fractureability of tight sandstones.Therefore,the method of fracturing of tight sandstone is studied,the fracturing coefficient suitable for the study area is constructed,and the fine fracturing interval is selected to provide scientific guidance for the development of tight sandstone oil and gas.This paper takes Ordos Area L as the research goal,and optimizes the parameters related to fracturing of tight sandstone reservoirs through geology,well logging,rock mechanics,and gas testing,and uses mathematical statistics and cross plots to fit the study area.The fracturing coefficient can be used to establish the evaluation index of the fracturing property in the study area.The main achievements and understanding are as follows:(1)Triaxial rock mechanics experiments,rock acoustics experiments,and Brazilian splitting experiments were performed to study the mechanical characteristics of tight sandstone rock in the study area.The brittleness index of rock samples was determined by the stress-strain curve.The lithology has little effect on rock brittleness index.In the rock fracture test,when the brittleness index is greater than 65%,the rock fractures develop well.According to the rock acoustics experiment,the velocity of the shear wave decreases and the anisotropy of the transverse wave increases after seaming.The fracturing effect can be judged based on the shear wave anisotropy.(2)Extraction of dipole acoustic logging data,extraction of P-and S-wave time differences,calculation of reservoir rock mechanics parameters through P-and S-wave time difference data,fitting of dynamic and static rock mechanics parameter models,and calculation of brittleness index and mineral composition with rock mechanics experiments The calculation of the rock brittleness index comparison shows the applicability of logging data in the area.The Huang's in-situ stress model is selected to calculate the maximum and minimum horizontal in-situ stress.The smaller the minimum horizontal in-situ stress,the higher the reservoir production capacity.(3)Divide the capacity level and study the influencing factors of post-pressurization capacity.After the pressure,open flow increases with brittleness index and decreases with increasing fracture toughness.When the brittleness index is greater than 50%,When the horizontal stress difference coefficient is greater than 0.1%,industrial airflow is obtained after fracturing.(4)Geological differences exist in tight sandstones in different regions.There are differences in the evaluation methods of fractureability in different regions.Through the evaluation of compressibility of tight sandstones,the brittleness index,horizontal stress difference coefficient,and compressive strength combined with fracture toughness are selected.The fracture coefficient analyzes the fractureability in L area,and establishes the evaluation index of fractureability in L area and practical application.Through the above data processing,model selection and other studies,the evaluation of the tight sandstone brittleness coefficient in the L area of Ordos Basin,combined with the fracture toughness to establish the fracturing model of the study area,provide a screening for the fracturing interval in the study area.