Study on Hydraulic Fracturing of Low Permeability Reservoir
|School||Wuhan Polytechnic University|
|Keywords||low permeability reservoirs hydraulic fracturing fluid-solid coupling crack opening numerical simulation|
With China’s rapid economic development and social progress, the energy problem will be restricting our rapid economic and social development of a bottleneck, the development of low permeability reservoir solution will become an important aspect of the oil crisis. Hydraulic fracturing of low permeability reservoirs to improve harvesting as an important means of effective, low-permeability oil reservoir in the very extensive use. But most of these low-permeability reservoirs, "three lows" reservoirs (stocks low abundance, low permeability, low oil production), mainly composed of these fields is strongly influenced by lithology factors constitute a complex of reservoirs, storage Comparison of sand scattered mostly narrow band, large lateral changes in lithology, permeability is low, water relations are complicated, the existing application of hydraulic fracturing technology in a variety of problems arising in the course, so the oil of low permeability Hydraulic pressure reservoir problems arising in the course is urgent.Based on the fluid - solid coupling theory, mechanics, plastic and rock fracture mechanics, damage mechanics, study of the perforation parameters, the weak layer scurrying layer, natural cracks and faults and other effects of several major effect of hydraulic fracturing in low permeability reservoir factors, through theoretical analysis and numerical simulation revealed that: (1) hydraulic fracturing in the perforation orientation angle changes will affect crack initiation of hydraulic fracturing stress and displacement; (2) hydraulic fracturing cement casing contacts with the rock is that the weak side, in the contact stress and displacement generated at the stress singularity phenomenon, resulting in fracturing fluid layer channeling most of them in there; (3) low permeability reservoir of water, the native will beat crack cracking and crack main crack extension, the greater the number of primary cracks, the main crack stress and displacement will be smaller; (4) When water fracturing multiple layers simultaneously, each reservoir crack initiation and expansion of mutual influence will be , and the interlayer thickness are smaller, the greater the impact, and by the middle of the crack is very clear on both sides of the crack; (5) low-permeability reservoirs in the fault will affect the effect of hydraulic fracturing, fault inclination changes will affect the hydraulic fracturing of the velocity and pressure in the fracturing fluid flow near the fault dramatic changes, the smaller the angle, the smaller the velocity near the fault, while the pressure gradient near the fault is greater.Based on the above findings, for hydraulic fracturing in low permeability reservoir fracturing parameters provide a theoretical basis.