The Recovery Potential Of Tight Gas Pool--Take XingChang Gas Field As Example

This gas reservoir is an elastic drive overpressured tight low-permeable dry gas one which is controlled and enclosed by structure and rock and whose volume is constant. There is a obvious difference between tight low-permeable and common gas reservoirs. Fissures not only are the main flow seepage and important storage space of natural gas, but also control the system and distribution of natural gas' seepage, thus they determine the effect of exploration and development of gas-field in tight low permeability gas reservoir. Taking geology as the main line of research and uniting a lot of research methods and subjects, synthetical studies and main achievements are as follows.1. By studying non-homogeneous character of reservoir, results is: key to that this gas reservoir can be developed is that there are a lot of independent permeable reservoir body in reservoir; these permeable reservoir body has definite permeable capacity of reservoir body. By studying the formation of gas reservoir and the characteristics of fissure, the results confirm: very development of low angle to horizontal fissures are ones of uplifting and unloading, and it is fissures of uplifting and unloading that help to bring about the formation of permeable reservoir body, the scale of permeable reservoir body is estimated.2. The characteristics of the stress field is gotten by making full use of the structural configuration and core's traces acted by stress field. Based on the test parameters of rock mechanics and on-site measurement of earth stress, three-dimensional- o software is utilized to simulate the stress field of objective formation numerically, and the relationship of the simulated stress field is: most maximum principal stress > vertical principal stress > minimum principal stress. The value of stress is low, and structural deformation is weak. The main body direction of maximum principal stress is about 156 . Stress' profile gained by log data indicates: there is stress difference between gas producing formations and interlayer, interlayer plays good barrier role in the vertical extension of hydraulic sand fracturing.3. The two important factors effecting on production are reservoir factors and artificial fracture based on results of well tests analysis after 13 gas wells were fractured; by modern production decline analyzing the factors of reservoir and fracture of 5 wells, their results are: available half-length of fracture is shorter, because the restricted layer of permeable reservoir bodyhold back extension of fracturing. The reasonable probation plan is made by analysis gas productivity curve.4. Based on production decline analysis, gas productivity curve analysis and well tests analysis, reservoir potential have a close connection with formation parameter and permeability. The Qaof is improved with higher efficient KH and K value. Meanwhile, the Qaof have power index relationship with half length of fracture. The nature of fracturing is to improve the seepage pattern, as a result, the production is improved.