Development of a comprehensive workflow for combined analysis of flowback and post flowback production data from multifractured horizontal wells completed in gas shales

利用多分支/多裂缝水平井从致密油气资源中开采油气，在北美迅速发展。然而，要高效、负责任和可持续地开发这种非常规能源，需要对所涉及的大规模压裂作业进行具有代表性的评估。非常规天然气聚集的一个例子是不列颠哥伦比亚东北部的霍恩河地层。据估计，该地层的页岩中储存着高达500Tcf的天然气，使其成为北美第三大天然气聚集区。描述霍恩河页岩中诱导的裂缝网络是一项具有挑战性的任务，主要是因为1)岩石是自然裂缝，因此水力压裂会导致复杂的裂缝网络，2)压裂作业后，当油井排液时，立即产生水和天然气。拟议的研究计划将开发一种工作流程，以分析在生产阶段的不同时间尺度上测量的天然气和水的压力和流量。研究任务将由两名博士生、两名硕士学生和一名博士后研究员在两个平行的研究阶段进行。第一阶段将模拟气体和压裂水的两相流动，以匹配早期排液数据。第二阶段将模拟天然气在复杂系统中的流动，该系统由水力裂缝、重新激活的天然裂缝和页岩基质组成，用于历史匹配回流后的生产数据。这项研究的结果将有助于该行业估计诱导裂缝的体积、长度和导流能力，从而更准确地评估压裂作业、预测天然气产量和估计总天然气储量。

Extraction of oil and gas from tight hydrocarbon resources by using multi lateral/multi fractured horizontal wells is rapidly growing in the North America. However, efficient, responsible and sustainable development of such unconventional energy resources requires representative evaluation of massive fracturing operations involved. An example of unconventional gas accumulations is the Horn River Formation in northeastern British Colombia. It is estimated that up to 500 Tcf of natural gas is stored in the shale members of this formation, making it the third largest North American natural gas accumulation.Characterizing the fracture network induced in the Horn River shales is a challenging task primarily because 1) the rock is naturally fractured and therefore hydraulic fracturing results in a complex fracture network, and 2) water and gas are immediately produced when wells are put on flowback after the fracturing operations.The proposed research program will develop a workflow to analyze pressure and flow rate of gas and water measured at different time scales of the production phase. The research tasks will be conducted by two PhD students, two MSc students, and a postdoctoral fellow in two parallel research phases. Phase 1 will simulate two-phase flow of gas and fracturing water for history matching the early-time flowback data. Phase 2 will simulate flow of gas through a complex system consisting of hydraulic fractures, reactivated natural fractures, and shale matrix for history matching post flowback production data. The outcomes of this research will help the industry to estimate the volume, length, and conductivity of induced fractures that will lead to more accurate evaluation of fracturing operations, forecast of gas production, and estimation of total gas reserve.