致密油藏水平井注CO_(2)开发效果评价

Evaluation of CO_(2) injection development effects of horizontal wells in tight reservoirs

致密油藏存在储层物性差、微裂缝发育、非均质性强和水驱开发动用程度低等问题,而CO_(2)驱和水平井开发技术能够起到提高采收率的作用,因此有必要针对致密油藏水平井注CO_(2)的不同开发模式进行效果评价。首先,建立目标致密油藏概念模型,采用LGR离散裂缝表征技术模拟水平井体积压裂后的裂缝网格形态,分别研究水平井注CO_(2)隔井吞吐及异步注采的开发效果;然后,调整优化最佳开发模式下的注采参数,明确致密油藏水平井注CO_(2)开发的合理注采参数,并利用Shapley值分析各注采参数对累计产油量的影响程度。结果表明:对于致密油藏,水平井注CO_(2)隔井吞吐开发效果远优于水平井注CO_(2)异步注采;水平井注CO_(2)隔井吞吐开发模式下的合理注采参数为注入速度100 t/d、焖井时间60 d、采液速度20 m_(3)/d、吞吐2轮次,各注采参数对累计产油量的影响程度从大到小排序为采液速度、焖井时间、注入速度、吞吐轮次。文中研究成果对致密油藏开发具有较好的借鉴意义。

Tight oil reservoirs have problems such as poor reservoir physical properties,microfracture development,strong heterogeneity and low exploitation and utilization degree of water flooding.However,CO_(2) flooding and horizontal well development technology can improve the recovery degree.Therefore,it is necessary to evaluate the development effects of different modes of CO_(2) injection in horizontal wells of tight oil reservoirs.Firstly,a conceptual mechanism model of the target tight oil reservoir is established,and the fracture grid morphology of horizontal wells after volumetric fracturing is simulated by using LGR discrete fracture characterization technology to study the development effects of CO_(2) huff-and-puff in isolated horizontal wells and asynchronous injection and production respectively.Then,under the condition of optimal development mode,the injection and production parameters are adjusted and optimized to determine the rational injection and production parameter for CO_(2) injection of horizontal wells in tight oil reservoirs,and Shapley values are used to analyze the impact of various injection and production parameters on cumulative oil production.The results show that the development effects of CO_(2) huff-and-puff in isolated horizontal wells is much better than asynchronous injection and production of CO_(2) in horizontal wells of tight oil reservoirs.The optimal injection and production parameters of CO_(2) injection in isolated horizontal wells are as follows:injection speed is 100 t/d,well soaking time is 60 d,liquid production speed is 20 m_(3)/d,huff-and-puff cycle is 2 rounds.The influence order of the effects of injection and production parameters on cumulative production is as follows:liquid production rate,well soaking time,injection rate,huff-and-puff cycles.The research results in the article have good referential significance for the development of tight oil reservoirs.