大牛地气田奥陶系碳酸盐岩气藏水平井产能主控因素评价

Evaluation of main factors affecting horizontal well productivity for the Ordovician carbonate gas reservoir in Daniudi gas field

任广磊 罗勇 高志彬

中国石化华北油气分公司勘探开发研究院，河南 郑州 450006 西南石油大学油气藏地质及开发工程国家重点实验室，四川 成都 610050 中国石油川庆钻探工程有限公司地质勘探开发研究院，四川 成都 610056

Research Institute of Exploration and Development, North China Oil and Gas Company, SINOPEC, Zhengzhou 450006, China State Key Laboratory of Oil and Gas Reservoir Geology and Development Engineering, Southwest Petroleum University, Chengdu 610050, China Research Institute of Geological Exploration and Development, CNPC Chuanqing Drilling Engineering Co., Ltd., Chengdu 610056, China

碳酸盐岩气藏微观孔隙结构和渗流特征复杂，无阻流量与地质、工程参数相关性差，单一统计方法不能有效评价水平井产能的主控因素。为此，文中提出一种新的产能主控因素评价方法，即在气井动态分类上，用Pearson，Spearman相关系数和决策树评分法对影响因素进行打分和排序，选择更具代表性的产能评价指标，逐类逐井评价。将新方法应用于大牛地奥陶系气藏37口压裂水平井评价，结果表明：1）水平井初期3~6个月平均产量比采用“一点法”得出的无阻流量更适合作为产能评价指标；2）Ⅰ，Ⅱ类气井，地层系数、含气性是其产能的主控因素，但储层物性掩盖了水平井长度、压裂级数的重要性；3）Ⅲ类气井，储层物性总体较差，水平井长度和压裂级数是其主控因素。新方法明确了将裂缝￣溶蚀孔洞发育、含气性好、有效厚度大的优质储层作为部署靶点，同时，有必要通过优化水平井长度和压裂级数来提高孔隙型储层水平井产能。

The micro pore structure and seepage characteristics of carbonate gas reservoir are complex, and the correlation between the absolute flow(AOF) and geological and engineering parameters is poor, so the single statistical method can not effectively identify the main control factors of horizontal well productivity. A new evaluation method of main control factors of well productivity is proposed. For the gas well dynamic classification, the influencing factors are scored and sequenced by Pearson, Spearman correlation and decision tree scoring method, and the representative production capacity evaluation index is selected to evaluate each well according to its classification. The new method is applied to evaluate 37 fractured horizontal wells in Daniudi Ordovician gas reservoir. The result shows: (1) the average production in the initial 3—6 months of horizontal wells is more suitable for productivity evaluation index than AOF obtained by "one-point method"; (2) for class Ⅰ and Ⅱ gas wells, the formation coefficient and gas content are the main control factors of gas well productivity, but reservoir physical properties cover up the importance of the length of horizontal wells and the fracturing stages; (3) for class Ⅲ gas wells, the physical properties of the reservoir are generally poor, and the length of horizontal wells and fracturing stages are the main control factors. The new method makes it clear that high-quality reservoirs with developed fractures-dissolved pores, good gas-bearing property and large effective thickness are selected as deployment targets, meanwhile, it is necessary to improve the productivity of horizontal wells of porous reservoir by optimizing the length of horizontal wells and the number of fracturing stages.

10.6056/dkyqt202101019