川西北超深层复杂构造气藏裂缝建模方法及开发潜力预测

针对川西北栖霞组海相碳酸盐岩气藏构造复杂、超深埋藏、高温高压、储层薄、裂缝发育等地质特点,基于三维地震数据,采用蚂蚁追踪技术和嵌入式离散裂缝数值模拟方法,编制嵌入式离散裂缝数值模拟器,优化气藏开发参数,预测气藏开发潜力。研究结果表明:气藏开发前期更适合用蚂蚁追踪技术来预测天然裂缝,嵌入式离散裂缝数值模拟器在捕捉流体在裂缝中的运移方面具有常规油藏模拟器无法比拟的优势,可显著提高裂缝性气藏数值模拟精度;优化栖霞组气藏合理开发井型为大斜度井或水平井,合理开发井距为1 600~1 800 m,水平井最优长度为600 m,人工裂缝最优半长为100 m。研究成果对同类碳酸盐岩气藏高效开发具有借鉴意义。

Fracture Modeling Method and Development Potential Prediction of Ultra-deep Gas Reservoirs with Complex Structure in Northwestern Sichuan

Aiming at the geological characteristics of marine carbonate gas reservoirs in Qixia Formation in northwest Sichuan such as complex structure, ultra-deep burial, high temperature and high pressure, thin reservoirs and well-developed fractures, an embedded discrete fracture numerical simulator was prepared with ant tracking technology and embedded discrete fracture numerical simulation method on the basis of 3D seismic data to optimize the parameters of gas reservoir development and predict the development potential of gas reservoirs. The results showed that, it was more suitable to employ ant tracking technology to predict natural fractures in the early stage of gas reservoir development, and the embedded discrete fracture numerical simulator, compared with conventional reservoir simulators, had incomparable advantages in capturing the fluid that migrated in fractures, significantly improving the numerical simulation accuracy of fractured gas reservoirs; the development well type was optimized as highly deviated well and horizontal well for Qixia Formation gas reservoirs, the reasonable spacing between development wells was 1,600 to 1,800 m, the optimal length of horizontal well was 600 m, and the optimal half-length of artificial fracture was 100 m. There is much for reference of the study results for the efficient development of similar carbonate gas reservoirs.