摘要: |
在缝洞型油藏中裂缝作为储集空间及渗流通道,其闭合与否对油田生产有着重要影响。以塔河缝洞型油藏为背景,对裂缝是否闭合进行预测,建立考虑内压变化的有限元力学模型,获得不同形态裂缝闭合过程及闭合规律。通过正交试验设计研究多因素对裂缝闭合的影响,并借助多元回归分析方法建立裂缝宽度随裂缝倾角、裂缝长度、侧压力系数变化的预测模型。结果表明:裂缝的长度越长、所处地层侧压力系数越大,裂缝越容易闭合;倾角对裂缝闭合的影响与所处地应力场有关,在构造应力小于垂直应力的地层中,倾角越小的裂缝越容易闭合;侧压力系数对裂缝闭合影响最大,裂缝长度次之,裂缝倾角影响最小。 |
关键词: 缝洞型油藏 裂缝长度:侧压力系数:裂缝倾角 预测模型 |
DOI:10.3969/j.issn.1673-5005.2016.01.012 |
分类号::TE 344 |
基金项目:国家自然科学基金项目(41172268,51279093);国家科技重大专项(2011ZX05014) |
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Prediction model for fracture width changes in vug-fracture oil reservoirs and its application |
WANG Chao1, ZHANG Qiangyong1, LIU Zhongchun2, ZHANG Yue1, LI Xingjun1
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(1.Geotechnical and Structural Engineering Research Center of Shandong University, Jinan 250061, China;2.Research Institute of Petroleum Exploration and Production, SINOPEC, Beijing100083, China)
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Abstract: |
In vug-fracture oil and gas reservoirs, the fractures are not only the main reservoir space, but also the seepage channels between the vugs and caves, so the opening and closure of the fractures have an important influence on oil and gas production. In order to predict the variations of the fracture width, a finite element mechanical model was established, based on the geological data from Tahe Oilfield, considering the change of internal pressure, in which the closure process of the fractures under different conditions can be simulated. The effects of various factors on the closure of fractures were analyzed via an orthogonal testing method. Based on multivariable regression analysis, a model to predict the variation of the fracture as a function of fracture dip, fracture length and lateral pressure coefficient was established. The simulation results show that fractures with a longer length and a larger lateral pressure coefficient are more vulnerable for closure. The effect of fracture dip on fracture closure can be influenced by the local stress distribution. In the strata that the tectonic stress is smaller than the vertical stress, the fractures with smaller dip are easier to close. The lateral pressure coefficient has a larger effect on the closure of fractures than that of the fracture length and fracture dip. |
Key words: vug-fracture oil reservoir length of fracture lateral pressure coefficient fracture dip prediction model |