Theory And Technology Research Of Xujiahe Deep Fractured Gas Reservoir Fracturing In West Sichuan

Xujiahe formation gas reservoir is the candidate base for reserves and outcome growth of Southwest Oil and Gas Field Branch in the period of Eleventh Five-Year Plan and medium-long time; it is also the important energy replacement domain in the 21st century. The majority of pore spaces in western Sichuan Xujiahe formation are emposieu and fracture, it generally has characteristics of low porosity, low permeability, high water saturation, micro pore, mini throat, high median pressure, strong heterogeneity; and it is the typical tight/hyper-tight fractured and pored reservoir, so it needs taking effective stimulation to improve producing reserves of low permeability layer. In western Sichuan Xujiahe area, it has many difficulties in implementing hydraulic sand fracture such as the well-developed natural fracture, the multi-fracture grave filtration; fine sandstone and hard siliceous cement, the high Young's modulus ,high fracture pressure; high treating pressure caused by high burial depth and the great friction of tube in during fracture,et.al. which cause falilure of fracture because it has no method to improve the discharge rate. This paper takes systemically research on fracturing theory and applied technology of deep zone tight-fractured gas reservoir in western Sichuan Xujiahe formation, and has acquired the following results:(1)By synthetically using of rock mechanics and elasticity, it forms wellface stress field model of the barefoot completion and the perforated completion after mud damaged formation, which provides theory calculate measure of reservoir fracture pressure predict for the high fracture pressure of tight gas reservoir.(2)Based on dynamics and static state rock mechanics testing of PLB block, associated fracturing data, builted up relational expression of the block dynamics and static state rock ,and model of layered earth stress, and acquires vertical layered stress section of the single well.(3)The reaction mechanism between individual mineral and conventional sandstone acidizing acid by laboratory experimental test,and the influence of mud immerse on rock mechanics. quantitative computing methods of forecasting the fracture pressure after acid pretreatment by using the principle of rock damage mechanics,which can relatively accuracy forecast fracture pressure of the block(inaccuracy less than 10%).(4)It systemically describes multi-fracture generating mechanism and eliminating technology, with the consideration of geologic characteristic and engineering practice in Xujiahe area, and do some research on multi-fracture generating mechanism and many technologies of reducing filtration and preventing multi-fracture, which include proppant slug, selection of fracturing materials, optimizing treating parameters etc.(5)According to gas reservoir physical properties in Xujiahe formation area, it brings forward performance requirements of fracturing fluid system, optimizes medium-high temperature and low friction fracturing fluid additive through laboratory experiment, and evaluates overall performance of this optimized and debugged fracturing fluid. By Testing proppant conductivity under various forms and grain diameter match, which provides new method for optimizing proppant in Xujiahe deep-seated gas reservoir fracturing.(6)research outcome applied to the gravel input fracture reform of western Sichuan PLB formation and acquired the first successful.