GEOLOGICAL RESEARCH
SUN Yongliang, CHEN Qi, ZHANG Ze, LI Guoliang, FANG Jiwei, NAN Xuefen
The well pattern in the developed enrichment areas of Su X block of Sulige Gas Field is gradually improving. Due to the poor geologic conditions in the peripheral areas, it is necessary to study the distribution of remaining gas in the enrichment areas and well pattern thickening programs in order to keep stable production in the block. Based on the characteristics of tight gas reservoir with low permeability and fracturing production, the conventional numerical simulation method is optimized. The method of capillary pressure scaling and balance initialization, reservoir classification and phase-permeability control, local adjustment of permeability and conductivity to simulate fracturing production and fine fit gas well production and flowing bottom hole pressure, is designed to quantitatively characterize the distribution of remaining gas and optimize the remaining enrichment areas by simulating the changes of formation pressure and reserve abundance. Based on analyzing the factors affecting the remaining gas distribution from the aspects of geology and development, and integrating the distribution characteristics of the existing well patterns, effective reservoirs and remaining reserves, the remaining reserves are qualitatively divided into four types: well pattern uncontrollable, blocking zone in composite sandbodies, loss circulation in horizontal wells and imperfect perforation. Then, for different types of remaining reserves, the infill modes are demonstrated and the infill wellsites are optimized, the infill programs are established, and the development indices are predicted. Eight infill wells were implemented in SX-11-11S test well area, the comprehensive evaluation showed that classⅠwells accounted for 87.5%, and the predicted recovery factor increased by 8.2%, with good results.