基于EDFM的页岩油水平井注水吞吐优化研究  

Optimization of huff-n-puff in shale oil horizontal wells based on EDFM

作　　者：曹小朋 刘海成[1] 李忠新[1,2] 陈先超 江朋宇 樊浩 CAO Xiaopeng;LIU Haicheng;LI Zhongxin;CHEN Xianchao;JIANG Pengyu;FAN Hao(Research Institute of Exploration and Development,Sinopec Shengli Oilfield Company,Dongying,Shandong 257015,China;School of Geosciences,China University of Petroleum(East China),Qingdao,Shandong 266580,China;College of Energy,Chengdu University of Technology,Chengdu,Sichuan 610059,China)

机构地区：[1]中国石化胜利油田分公司勘探开发研究院,山东东营257015 [2]中国石油大学(华东)地球科学与技术学院,山东青岛266580 [3]成都理工大学能源学院,四川成都610059

出　　处：《油气藏评价与开发》2024年第5期734-740,共7页Petroleum Reservoir Evaluation and Development

基　　金：中国石化科技攻关项目“深洼带及复杂断块页岩油开发优化设计技术”(P22037)。

摘　　要：陆相页岩油水平井自然产量递减快、采出程度低,而单井注水吞吐能有效补充地层能量并提高采出程度。以鄂尔多斯长7段页岩油为例,采用数值模拟方法,开展陆相页岩油水平井注水吞吐优化研究。为了提高页岩油藏体积压裂后数值模拟模型的准确性,引入EDFM(嵌入式离散裂缝模型)来表征储层天然裂缝和体积压裂形成的水力裂缝,建立了综合考虑渗吸作用以及储层应力敏感性的概念模型。对注水时机、注水量、注水速度、焖井时间和吞吐周期进行优化选择,数值模拟结果表明:注水速度过快,水容易沿裂缝窜流,导致注入水利用率降低;随吞吐周期增加,每轮周期内增油量呈下降趋势。针对模型所参考的鄂尔多斯某页岩油藏而言,注水吞吐参数优化为:压力系数降至0.706时进行注水,注水量优选为4000 m^(3),注水速度为300 m^(3)/d,焖井15 d,进行6轮吞吐,最终能将采出程度提高4.95%,总油水置换率达到6.65%。该研究能为页岩油藏注水吞吐研究提供参考。Continental shale oil horizontal wells have fast decreasing natural production and low recovery,for which single well water injection huff-n-puff can effectively replenish formation energy and improve recovery.Taking Ordos Chang7 shale oil as an example,numerical simulation method is used to carry out the optimisation study of water injection huff-n-puff in horizontal wells of continental shale oil.To enhance the accuracy of the numerical simulation model for shale reservoirs after volume fracturing,the Embedded Discrete Fracture Model(EDFM)is introduced.This model characterizes both natural and hydraulic fractures resulting from volume fracturing.Additionally,a conceptual model that considers imbibition and reservoir stress sensitivity is established.The timing,volume,and speed of injection,as well as the soaking period and huff-n-puff cycle,are optimized based on simulation results.These results indicate that a too-rapid injection rate causes water to flow along the fractures,decreasing the utilization rate of the injected water.As the huff-n-puff cycle increases,the oil increment per cycle tends to decrease.For the specific case of a shale reservoir in Ordos,the optimization of huff-n-puff parameters is as follows:Water injection should commence when the pressure coefficient drops to 0.706,with an optimal injection volume of 4000 m^(3)at a rate of 300 m^(3)/d.The recommended soak period is 15 days,with a total of six huff-n-puff rounds.This approach can increase the recovery rate by 4.95%and achieve a total oil-water replacement rate of 6.65%.This study provides valuable insights for water injection huff-n-puff strategies in shale reservoirs.

关 键 词：页岩油 注水吞吐 数值模拟 EDFM 参数优化 

分 类 号：TE357[石油与天然气工程—油气田开发工程]