A Comprehensive Work Flow To Characterize Waterflood-Induced Fractures by Integrating Real-Time Monitoring, Formation Test, and Dynamic Production Analysis Applied to Changqing Oil Field, China
A Comprehensive Work Flow To Characterize Waterflood-Induced Fractures by Integrating Real-Time Monitoring, Formation Test, and Dynamic Production Analysis Applied to Changqing Oil Field, China
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DOI：
10.2118/191370-pa
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发表时间：
2018-08
影响因子：
2.1
通讯作者：
Yang Wang;Shiqing Cheng;Kaidi Zhang;Youwei He;N. Feng;Jiazheng Qin;Le Luo;Haiyang Yu
中科院分区：
文献类型：
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作者：
Yang Wang;Shiqing Cheng;Kaidi Zhang;Youwei He;N. Feng;Jiazheng Qin;Le Luo;Haiyang Yu
在致密油藏中，注水会导致地层压裂，这是众所周知的。特别是当现场地质条件复杂，水驱裂缝(WIF)不能及时识别时，诱发裂缝可能与井距处于同一级别，这对平面波及和垂向整合都有显著的(通常是不希望的)影响。因此，必须及时确定水驱开始的时间，并对水驱动态进行全面评估，以便随着时间的推移制定适当的战略。应用基于流量/井底压力和地层测试资料的分析/半解析、统计和数值技术的新工作流程，在长庆油田识别含水率、诊断注水方向和前缘分布、分析井间连通性和解释井底压力异常动态。该工作流程包括三个模块：首先，使用实时监测和分析，包括改进的霍尔图、演变皮肤分析和注入/压裂指数方法，以识别WIF的起点。在此基础上，利用由阶跃率测试(SRT)、放射性示踪测井和被动地震法组成的地层测试模块，研究了地层破裂压力以及平面和垂向水驱动态的不均质性。在前两个模型的基础上，采用注采关系模型(IPRS)和约束多元线性回归(MLR)方法，利用注采比定量研究注采方向。提出了一种新的模型-注水压裂井(IWWIF)，用于描述水驱压裂井的异常行为，该模型考虑了水驱压裂井在衰减期的性能变化(裂缝长度缩小和导流能力降低)。与单个方法相比，开发了ITD(WIF识别、地层测试和动态产量分析的缩写)工作流程，以全面、深入地了解注水开发动态。这项研究的主要重点是整合不同的方法来解决关键的不确定性，而不是单独分析每个数据源。在此工作流程的基础上，运营商可以更主动、更合理地做出水驱管理决策。本文提出的工作流程对致密油藏短期和长期注水开发管理具有一定的指导意义。
It is well-known that water injection may induce formation fracturing in tight reservoirs. Especially when the field-geology condition is complex and the waterflood-induced fractures (WIFs) are not well-identified in time, the induced fractures can be of the same order as the well spacing, which has a significant, and generally undesired, impact on both areal sweep and vertical conformance. Therefore, the onset of WIFs must be identified in a timely manner, and the waterflooding performance must be evaluated comprehensively to formulate an appropriate strategy over time. A new work flow, containing analytical/semianalytical, statistical, and numerical techniques that are based on flow-rate/BHP and formation-testing data, is applied to identify the WIFs, diagnose waterflooding direction and front distribution, analyze interwell connectivity, and interpret abnormal bottomhole-pressure (BHP) behaviors in the Changqing Oil field. The work flow includes three modules: First, real-time monitoring and analysis, including modified Hall plot, evolving skin analysis, and injection/fracturing index methods, are used to identify the start of WIFs. Then, the formation-testing module, consisting of step-rate test (SRT), radioactive-tracer logging, and passive seismic method, is applied to investigate the formation-fracturing pressure, and uneven waterflooding performance in the areal and vertical directions. On the basis of the two former modules, we adapt the third module, which includes injector/producer relationships (IPRs) and the constrained multiple-linear-regression (MLR) method, to quantitatively investigate the waterflooding direction by injection/production rates. A new model—injection well with waterflood-induced fracture (IWWIF)—is proposed to characterize the abnormal BHP behaviors considering the properties variation (shrinking fracture length and decreasing fracture conductivity) of WIFs during the falloff period. Compared with an individual method, the ITD (which is the abbreviation of WIF identification, formation testing, and dynamic production analysis) work flow is developed to obtain a comprehensive and deep understanding of waterflooding performance. The main emphasis of this study is to integrate different approaches to address the key uncertainties rather than analyze each data source individually. On the basis of the results obtained by this work flow, the operators can make a more-proactive and -reasonable decision on waterflooding management. The work flow proposed in this paper gives a useful guidance in short- and long-term waterflooding management in tight reservoirs.