Research And Application Of Numerical Simulation Of In-situ Stress And The Stimulation With Fracturing In Daqing Volcanic Gas Reservoir

With entering the development phase of high water content, and decreasing production in Daqing oil field, it is strategic importance to supplement oil by natural gas, and implement developing oil and natural gas simultaneously for the sustainable development of Daqing oil field, and creating a century oil field. With the constant developing of the exploration, a large area of natural gas reservoirs in volcanic rocks was found in Xujiaweizi in the northern part of the Songliao Basin. 100 billion cubic meters of ultra-large-scale natural gas field is discovered and verified. Volcanic reservoir become the main exploration target for finding natural gas. Volcanic gas reservoir in Daqing oil field have to be made effectual treatment with fracturing to produce commercial value for it's deeply buried, and it has high temperature,complex lithology, hard rock, dense structure, the existence of a large number of micro-cracks and holes and the low natural production capacity . Applying the stimulation with fracturing for sand shale in Daqing volcanic gas reservoir, the success rate of operation is only 36 percent. The result of the stimulation is bad. The stimulation with fracturing for volcanic gas reservoir has become one of the bottleneck techniques of restricting exploration and development in the natural gas reservoir.All the rocks' breaking and cracks' extending are mainly controlled by in-situ stress, and stress distribution in volcanic gas reservoir is complex. It results in fracturing difficult, and prone to giving rise to sand plugging, and no fracturing, and the low success rate of fracturing and so on. So the in-situ stress distribution becomes one of the important factors of restricting success of fracturing in volcanic gas reservoir. The principal stress distribution (including the size and direction) in different regions can be predicted by carrying on simulation technology research of volcanic region stress field. It brings realizing directly judge of difficulty degree of operation by the difference of the principal stresses, and provide a basis for taking targeted measures.In this paper, regional in-situ stress field simulation technology research was carrying out by finite element numerical simulation methods, and set up volcanic in-situ stress field distribution of A well block, and applying in-situ stress field simulation results, analyse the impact of local in-situ stress distribution on the stimulation with fracturing, and determine the appropriate evaluation criteria and treatment measures by well site test study to further improve the success rate of volcanic rock fracturing technology, and provide technical support for exploration and exploitation of deep natural gas.