Rock Pressure And Swelling Characteristics And Pressure Expansion Loose Increasing Technology Research

To loosen rock by the dilatancy with explosive wave is a new technology used since 1970s for the oil and gas well stimulation, and its basic principle is that through the supperposition of explosive wave the formation emerges dilatancy, then its porosity and permeability get a significant increase. Based on the laboratory work of sandstone and carbonate the two major reservoir rocks,paper looked for the conditions occurring dilatancy and it's influence to permeability, compressive strength and sonic velocity characteristics, in order to provide the basis theory to loosen rock by the dilatancy with explosive wave. In addition, the paper also conducted the research of explosion wave propagation and superposition in rock, designed the devices and construction process and testing.In this paper, the major works include:(1) A drop hammer loading experimental system to produce dynamic dilatancy has been developed, the sensors of the system has been calibrated. Experimental error is 5%.(2) The conditions occurring dilatancy had been discovered, the two basic conditions is : First, the nonuniform loading coefficientζis in the range of 0 to 0.3,when the nonuniform loading coefficient greater than 0.3, the rock cannot generate dilatancy; Second, the maximum principal stress is in the range of 1 / 2 to 2 / 3 of rock strength, when the maximum principal stress is less than the compressive strength of 1 / 2 to 2 / 3, the rock's volume cannot increase.(3) The mechanical properties after dilatancy had been tested,The permeability after dilatancy gets a significant increase , and some even increased three times. Permeability's increasing relates to nonuniform loading coefficient, with nonuniform loading coefficient increasing permeability decreases, the permeability increaseing ratio and nonuniform loading coefficient shows exponential relation., different rock has different index.(4) The elastic modulus and sonic velocity after dilatancy had been experimentalized ,The elastic modulus and acoustic propagation velocity both becomes lower.(5) The effect of dilatancy to hydraulic fracture parameters had been studied, at the tip end of fracture there is very high stress and dilatancy occurs during hydraulic fracturing, this can increase width and decrease length.(6) The superposition of the explosive wave and the method of superposition i rock had been researched, the delayed explosion wave superposition law of two an three points of burst had been done.(7) The devices and construction process had been designed , the charging structure, explosives choice had been derivated and computed.(8) Paper designed casing and downhole protection device.(9)The operating technology To loossen rock by dilatancy was formulated.(10)To stimulate by this method in 67 - P147 well of DaQing oil field ,the reservoir rock mechanics parameters were determined, the diameter of the charge and delay time were calculated , the experimental result was analyzed.