高CO含量气藏物质平衡方程及其动储量评价

Material Balance Equation and Dynamic Reserve Calculation of CO-rich Gas Reservoir

成涛 栾雪莹 王雯娟 刘鹏超 吕新东

CHENGTao LUANXueying WANGWenjuan LIUPengchao LüXindong

中海石油(中国)有限公司湛江分公司, 广东 湛江 524057 油气藏地质及开发工程国家重点实验室·西南石油大学, 四川 成都 610500

CNOOC China Limited, Zhanjiang Branch, Zhanjiang, Guangdong, 524057, China State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China

针对高CO含量天然气在气藏衰竭式开发过程中存在的溶解气释放效应导致动储量无法得到有效评价的问题，建立了考虑水侵、应力敏感效应、水蒸气含量以及溶解气释放效应的物质平衡方程。采用PVT实验研究了CO含量分别为3.18%~53.90%的天然气混合物在压力由53.01 MPa降低至3.01 MPa的溶解度变化情况，回归得到了溶解度的预测模型。为了研究高CO含量对气藏的动储量评价方面的影响，分别利用压降法、考虑应力敏感储量计算模型、考虑应力敏感、水蒸气含量及水蒸气膨胀量的储量计算模型，以及针对高CO含量提出的计算模型对A气藏动储量进行计算。研究结果表明，不考虑高CO含量天然气的释放效应计算得到的动储量结果普遍偏高，误差范围在（0.69~2.55）×10 m，因此，高CO含量天然气的释放效应在气藏的动储量评价过程中不能被忽略。

For an accurate calculation of dynamic reserve during the depletion-drive development of CO-rich gas reservoir, which is a consequence of release of dissolved gas, a material balance equation is established considering water encroachment, reservoir stress sensitivity, water vapor concentration, and release of dissolved gas. PVT experiments were performed to investigate changes in the solubility of natural gas mixtures with a CO concentration of 3.18%~53.90% when the pressure dropped from 53.01 MPa to 3.01 MPa. Based on the experimental results, a prediction model for solubility analysis was developed based on regression. To investigate the effect of high CO concentration on the dynamic reserve calculation of gas reservoirs, the latter (denoted by A) was calculated utilizing the pressure drop method, the reserve computation model only considering stress sensitivity, the reserve computation model considering stress sensitivity, water vapor concentration and water vapor expansion, as well as the proposed computation model that also considered high CO concentration. The results showed that when the effect of the release of CO-rich natural gas was not considered, the calculated dynamic reserves were considerably high, with errors ranging from 0.69×108 m to 2.55×10 m. Therefore, its effect cannot be ignored in the evaluation of the dynamic reserve of gas reservoirs.

10.11885/j.issn.1674-5086.2018.09.25.04