一种考虑长期导流的人工裂缝参数优化方法

A new optimal method on artificial fracture parameter with long-term conductivity taken into account

杨立峰 安琪 丁云宏 崔明月 许志赫

YANG Lifeng AN Qi DING Yunhong CUI Mingyue XU Zhihe

中石油勘探开发研究院廊坊分院，河北廊坊　065007 中国石油天然气集团公司油气藏改造重点实验室，河北廊坊　065007 中国石油新疆油田分公司风城油田作业区，新疆克拉玛依　834000

Langfang Branch of Research Institute of Petroleum Exploration & Development, Langfang 065007, China China National Petroleum Corporation the Key Laboratory of Reservoir Stimulation, Langfang 065007

无因次支撑指数法在人工裂缝参数优化时未考虑裂缝导流能力随时间变化对压裂井产能的影响，因此优化结果在实际生产时并非最优。结合支撑剂的长期导流实验结果，将无因次支撑指数法中的裂缝宽度和渗透率转换为时间变量的函数，并对无因次支撑指数法进行时间积分，求取最大的无因次累计生产指数，作为最优的裂缝参数优化结果。由于该方法引入了时间变量，考虑了支撑剂导流能力随时间的变化，因此较无因次支撑指数法更符合实际。研究结果表明，针对低渗、特低渗储层，在考虑长期导流能力的情况下，优化结果所需缝宽更大，支撑剂铺置浓度更高，改变了以往低渗、特低渗储层对人工裂缝导流能力要求不高、尽量造长缝的观点，对提高单井压后增产有效期和压后效果有重要意义。建议对特定区块开展有针对性的铺置浓度对支撑剂长期导流能力的影响规律研究，为无因次累计生产指数法的应用提供可靠的基础数据。

Artificial fracture parameter optimization with dimensionless proppant index method is an analytical approach widely used, but the effect of long-term artificial fracture conductivity performance change with time on the well productivity have not been taken into account. The optimization results by dimensionless proppant index method are not the best one in the view of practical production of stimulation wells. In this paper, combined with the experimental results of long-term proppant conductivity, transferring the fracture width and permeability in dimensionless proppant index method into the functions of time, the dimensionless cumulative productivity index has been presented though the integral of dimensionless proppant index with respect to time. And this result will serve as the optimal fracture parameter. Because of variable time being introduced into the formula and considering the change of proppant conductivity performance with time, the calculating method is more suitable in practice and more reasonable comparing to dimensionless proppant index method. The numerical solutions show that greater fracture width and higher concentration of proppant should be reached for low and extra-low permeability reservoirs with long-term conductivity taken into account in order to get more cumulative production. The views of lower demand artificial fracture conductivity and longer fracture for low and extra-low permeability reservoirs should be changed. This method can prolong the validity period of post-treatment production increase for single well and is of significance to evaluate operation effect. It is suggested that the influence of proppant concentration on long-term conductivity should be developed pertinently for certain areas, which could provides reliable reference for the application of dimensionless cumulative production index method.