裂缝性底水油藏储气库最大工作气量的预测方法

利用华北油田水驱开发晚期裂缝性碳酸盐岩块状底水油藏改建大型地下储气库，对保障京、津、冀等地区安全、平稳供气，具有重要意义。虽然前期对华北任11井裂缝性碳酸盐岩块状底水油藏改建地下储气库的可行性已开展了相关研究工作，但没有解决工作气量、气垫气量优化评价的关键技术问题。文章通过借鉴国外含水层储气库注采运行的经验，在物质平衡原理基础上，提出了描述裂缝性碳酸盐岩块状底水油藏改建地下储气库工作气量预测的数学模型。该模型能较准确地预测随油气界面下移，气库能达到的最大工作气量和相应气垫气量。通过实例求解得出注气增压系数对工作气量及其在库容量中所占的比例影响较大。随着注气增压系数的增大，工作气量及所占的比例迅速增加，气库效率随之提高，因此，提高注气增压系数是提高裂缝性碳酸盐岩块状底水油藏储气库效益的重要途径。

A METHOD PREDICTING THE MAXIMUM WORKING GAS VOLUME OF UNDERGROUND GAS STORAGE REBUILT ON THE FRACTURED BOTTOM-WATER OIL RESERVOIRS

Establishing large-scale underground natural gas storage rebuilt on fractured massive carbonate water-bottom oil reservoirs which are in the final water-drive development stage in Huabei Oilfield is very important to the secure and stable gas supply to Beijing, Tianjin and Hebei area. Though relevant earlier feasibility research works on rebuilding the fractured massive carbonate water-bottom oil reservoir to an underground gas storage of Ren 11 well in Huabei Oilfield was carried out, key technical problems have not been solved, including the optimal appraisal of the working gas and cushion gas volume. A mathematical model for prediction of working gas volume of this kind of underground natural gas storage was put forward via taking advantage of experience of aquifer gas storage in foreign countries on the basis of material balance principle. The prediction model can accurately predict the maximum volume of working gas and cushion gas, while gas-oil interface moves downwards. Examples of the model show that pressure coefficient has obvious effect on the volume of working gas and its correlative ratio. Along with the rise of the pressure coefficient, the volume of working gas, its correlative ratio and the efficiency of gas storages are increased too. Therefore, increasing the pressure coefficient is an important method to improve the benefit of the underground gas storage which is rebuilt on the fractured massive carbonate bottom-water oil reservoir.