页岩油藏“密切割”体积改造产能影响因素分析

Factors Influencing the Productivity of the Multi-fractured Shale Oil Reservoir with Tighter Clusters

"密切割"水平井体积改造是开发页岩油藏的有效手段,裂缝间距和井距是"密切割"水平井体积改造设计的关键环节。基于Comsol建立了离散裂缝网络数值模型,对"密切割"体积改造油藏进行仿真模拟,研究了裂缝间距、井距、裂缝复杂程度对增产效果的影响。结果表明,针对目标油藏,裂缝间距由30 m缩短至10m,单井累计产量可提高到原来的1.63倍;布置加密井,将井距从400 m缩短至200 m,目标储层年产量可提高51.17%;生产初期,复杂缝单井比简单缝单井90 d累计产量高39.80%。鉴于人工裂缝呈现非均匀充填的特征,采用等效加密方法表征的裂缝无法反映这一特点,研究了远端无支撑裂缝对改造效果的影响,发现远端无支撑裂缝对单井年产量的影响可达4.38%。"密切割"水力压裂矿场试验显示,采用细分切割的方法缩小裂缝间距,能够有效地提高油井产能,单井年产油可提高79.70%。

The multi-fracturing horizontal well with tighter clusters is an effective means of developing shale oil reservoirs.Fracture spacing and well spacing are key parameters in the tight cluster hydraulic fracturing design.A discrete fracture network numerical model based on Comsol software is established,simulating multi-fractured reservoir with tighter clusters.The effects of fracture spacing,well spacing and fracture complexity on the stimulation effectiveness are discussed.The results show that,for the target reservoir,the cumulative production of a single well can increase to about 1.63 times by decreasing fracture spacing from 30 m to 10 m.The cumulative production of the target reservoir can increase about 51.17%by decreasing the well spacing from 400 m to 200 m.The 90 d cumulative production of a single well with complex fracture is 39.80%higher than that with simple rectangular fracture.Tight cluster hydraulic fracturing field experiments show that artificial fractures have non-uniform filling characteristics.Fractures characterized by equivalent refining methods can′t reflect such characteristics.Therefore,the effects of the remote unpropped fracture on the stimulation effectiveness are also discussed.The effects of the remote unpropped fracture on the annual cumulative production of a single is about 4.38%.Field experiment shows that the multi-fractured horizontal well with tighter clusters could improve the single well production effectively by 79.70%.