South Western Sichuan Province To Gas Reservoir Fracturing Theory And Technology Research

Xujiahe formation, which has a large gas-bearing area, are widely dispersed in southwestern Sichuan, and its main gas-bearing section is t3x2. There are many reasons in Xujiahe areas lead to extremely difficulties for sand hydraulic fracturing. The deep lying formation have a high fracturing pressure. Natural fractures develop, and filtrate seriously. It requied work with large displacement to lower filtration, and to prevent sand blocking. Thus, the treating pressure would be very high. Formation is a fine sandstone lithology. They form narrow fractures because of their hard feature and high Young's modulus. It needs work with large displacement for sand blocking prevention, which is also lead to high treating pressure. The reservoir buried deep, and the pipe friction is large, whereas the treating pressure is limited, which induce the displacement couldn't be increased to the required value. Seen from the exploitation of t3x2 low permeability gas reservoir, an efficient Reservoir reconstruction measures not yet formed currently. Supporting technologies and effect of low permeability gas reservoir development lack a breakthrough.The present paper is specific to fracturing theory and technology of t3x2 gas reservoir in western Sichuan. We got the tectonic stress coefficient with logging data, experimental data of rock mechanics testing and fracturing treating data, set up a mechanical model for the stratified calculation of ground stress, and obtained the vertical stratification stress profile. By utilization of rock mechanics, elasticity and other knowledge, we set up a model for quantitative prediction of formation breakdown pressure for perforation completions of vertical wells while the reservoir was injuried, which Provided a basis for lowering treating risk and optimizing the technology. According to the physical conditions of t3x2 gas reservoir, we put-forward the requirements for fracturing fluid system performance, optimized low-friction and high temperature fracturing fluid additives, and envaluated the optimized fracturing fluid system. The study illustrated the formation mechanism and cancellation of multiple fractures Systematically, and investigated the formation mechanism of multiple fractures, various technologies including proppant slug, fracturing material selection and optimization of construction parameters for lowering filtration and fractures prevention combined with geological features of Xujiahe aera and reality of the project. Besides that, we came up with several technologies for lowering fracturing pressure for high fracturing pressure reservoir, and analyzed their adaptability.