页岩油气藏水平井井间干扰研究现状和讨论

低渗页岩储层难以自然形成工业油气流，常采用水平井和水力压裂建立人工缝网以保证商业化开采。然而，随着大规模加密布井和压裂，水平井间距缩小、储层改造体积增加，井间出现人工裂缝导致的干扰，影响邻井的井口压力和产量，甚至诱发井控、套损和支撑剂侵入等问题，严重时导致水平井报废，极大地影响生产效率。此外，老井亏空会导致储层地应力在原位地应力的基础上发生动态演化，形成复杂地应力状态，继而影响加密水平井和重复压裂井的储层改造效果，限制井平台产能表现。我国准噶尔盆地、四川盆地、鄂尔多斯盆地等地的页岩油气资源开发已进入小井距和加密布井阶段，井间干扰已对正常生产产生明显影响，急需开展针对性研究。本文对国内外页岩油气藏的井间干扰现象、机理以及诊断方法进行全面、详细的介绍，并提出干预对策。研究认为:准确表征与预测压裂水平井井间干扰需要在地质工程一体化的框架下展开；对天然裂缝、断层、原位地应力和储层岩石力学特征的准确认识是评价井间干扰的前提；地层亏空诱发的动态地应力和复杂人工缝网的建模与表征是定量评价井间复杂缝网交互与连通的关键手段，也是定量预测井间干扰对于井平台最终可采储量(EUR)影响的有效方法；关井、老井注液、重复压裂、优化井距和压裂优化都是干预或减小井间干扰的手段。

Research status and discussion of horizontal well interference in shale oil and gas reservoirs

Low-permeability shale reservoirs can hardly form industrial oil and gas flow naturally, and their commercial production is commonly realized by using horizontal well and hydraulic fracturing to create hydraulic fracture networks. As large-scale infill well deployment and fracturing is conducted, however, horizontal well spacing gets short and stimulated reservoir volume (SRV) is increased, so interference induced by hydraulic fractures occurs between wells, which impacts the wellhead pressure and production rate of the neighboring well and even induces the problems of well control, casing damage and proppant invasion and seriously results in the abandonment of horizontal well, so as to impact the production efficiency greatly. In addition, the depletion of old wells can lead to the dynamic evolution of reservoir geostress on the basis of the in-situ geostress to form the complex geostress state, which will impact the reservoir stimulation effects of infill horizontal wells and refracturing wells and restrict the productivity performance of well pads. The development of the shale oil and gas resources in the Junggar Basin, the Sichuan Basin and the Ordos Basin of China has stepped into the stage of small well spacing and infill well deployment, so well interference has already impact the normal production obviously. Therefore, it is in urgent to carry out specific studies. In this paper, domestic and foreign well interference phenomena, mechanism studies and diagnosis methods of shale oil and gas were introduced in details, and the intervention countermeasures were proposed. It is indicated that accurate characterization and prediction of fractured horizontal well interference shall be carried out in the framework of geology and engineering integration. The accurate understanding of natural fractures, faults, in-situ geostress and reservoir rock mechanical characteristics is the prerequisite to evaluate well interference. The modeling and characterization of formation depletion induced dynamic geostress and complex hydraulic fracture network is the key means to quantitatively evaluate the interconnection of complex fracture network between wells, as well as the effective method to quantitatively predict the impact of well interference on the estimated ultimate reserve (EUR) of well pad. Well shutdown, liquid injection into old well, refracturing, well spacing optimization and fracturing optimization are the means to intervene or diminish well interference.