Fracturing Geological Characteristics And Fracture Propagation Law Numerical Simulation Research In Block M

The C6 tight sandstone reservoir in Block M of Certain Oilfield has low fluid production in the early development stage.Wells with fluid production less than 20 t/d account for more than 85% of the total production wells.The influencing factors of the fracturing transformation effect are unclear.In this research,rock physical and mechanical properties test experiments and heterogeneity analysis were launched according to the fracturing geological characteristics of Block M,and numerical simulation was launched for the fracture propagation law.Detail are as follows:1.The rock physical and mechanical properties of C6 reservoir in Block M have been measured experimentally.The tensile strength,elastic modulus,Poisson's ratio,maximum horizontal principal stress,minimum horizontal principal stress and vertical stress of natural cores in C6 reservoir are given by Brazilian splitting test,triaxial stress test and Kaiser effect based acoustic emission test.The cohesion,brittleness and internal friction angle of rocks are calculated at the same time,which provides a precondition for predicting fracturing geological characteristic parameters of representative wells in C6 reservoir.2.By means of combining the measured results of rock physical and mechanical properties with field logging data,the prediction method of rock physical and mechanical properties parameters in M area is established,and the vertical interlayer,intralayer and plane heterogeneity of reservoir are quantitatively analyzed.The analysis results show that the vertical and plane heterogeneity of rock physical and mechanical properties of C6 reservoirs in Block M is stronger than that of plane heterogeneity.3.The true three-dimensional fracture propagation model is solved by finite element method,and the real simulation of hydraulic fracturing fracture propagation is realized by ABAQUS software.The effects of different elastic modulus differences on fracture propagation in C6 reservoir of Block M,the effects of different interlayer stress difference/elastic modulus on the thickness of fracturing fluid penetration and the effects of natural fractures on fracture propagation in water were simulated respectively.The results show that the decrease of elastic modulus from low to high fracture width and the difference of elastic modulus lead to concave and convex fracture profile,which results in difficulty in sand crossing at interface and smaller fracture height with larger difference of elastic modulus.Under the same conditions,the thicker reservoir thickness,larger construction displacement,larger difference of interlayer stress and greater difference of interlayer elastic modulus lead to greater net pressure and thickness of fracturing fluid crossing layer.When the fracture approaching angle and friction coefficient of natural fracture wall are fixed,the difficulty of natural fracture opening decreases gradually with the increase of stress difference;when the net pressure,stress difference and friction coefficient of natural fracture wall are fixed,the difficulty of natural fracture opening decreases gradually with the increase of fracture approaching angle.At the same time,when the net pressure in the fracture is 4MPa,it is the turning point of natural crack opening.When the net pressure is less than 4MPa,the natural crack will not open,and the hydraulic crack will extend through the natural crack in the original direction.