【作者】 刘钦节；

【导师】 闫相祯；

【作者基本信息】 中国石油大学 ， 油气工程力学， 2009， 博士

【摘要】 低渗油藏地应力场和储层裂缝的分布特征,对低渗油藏的油气运移、注采井网部署与调整、钻井管柱优化设计等都具有重要影响。但长期以来人们对石介质固有属性的认识存在一定的模糊性和局限性,对油藏地应力及储层裂缝的研究尚处于探索阶段。本文重点针对岩石力学参数、油藏地应力及储层裂缝预测分析研究中的热点和难点问题,在借鉴前人大量研究成果的基础上,利用现代数学、力学、计算机等知识通过理论推演、数值模拟、油田实例分析及配套软件开发等途径,提出适于低渗透油气储层的油藏应力场及储层裂缝分布规律的预测分析技术。首先,基于岩石声学特性和力学特性之间的关系推导了确定力学参数的模型方法,参照岩心测试数据结合最优化反分析技术利用油田现场大量的常规测井信息计算岩石力学参数,研究了储层岩石参数的随机性和模糊性,预测分析了储层岩石弹性模量及泊松比的概率分布类型,并计算得出其统计特征值。其次,推导分析了以关键井处地应力的大小和方位为约束条件,利用多井多目标约束的最优化技术确定储层岩石地应力分布规律的模型方法。实例计算表明约束井处地应力大小及方位误差皆能满足实际工程要求,并获取了研究区域储层平面内三向主应力、孔隙压力及破裂压力的分布规律,回归拟合了江苏油田三向地应力随深度变化的关系曲线。再次,根据储层岩石所受的复杂多轴应力环境,研究分析了储层岩石地应力状态函数和基于多强度参数的破坏曲面方程,建立了储层裂缝预测分析的多参数判据模型,有效弥补了常规岩石破裂准则中参数过于单一、无法考虑储层岩石非均质性和各向异性等缺陷。同时,为了考虑岩石材料原始微缺陷等对储层裂缝的影响,文中将位错理论引入到储层裂缝预测中,提出了基于位错模型的储层裂缝预测的新方法,为储层裂缝的分析预测提供了一种可行而有效的方法。在此基础上,开展了油气储层岩石强度参数的概率模型分析,提出了利用Monte Carlo法随机有限元模拟技术预测分析储层岩石裂缝发育情况的模型方法。江苏油田W油区实例分析结果表明,研究成果较好地分析预测了裂缝发育区域,并通过裂缝发育指数与裂缝密度间的拟合关系,预测分析了研究区域油藏储层裂缝密度分布规律。最后,设计开发了“地应力及裂缝预测分析系统(RSFA)”软件,为论文的理论研究成果较全面、方便地应用于油田生产实际提供了一个有效途径,初步实现了论文理论方法向工程实际应用的转化。更多还原

【Abstract】 The distribution characteristics of stress fields and reservoir fractures of the low permeability reservoir play an important role in the hydrocarbon migration, well patterns arrangement and adjustment, optimization design of drilling strings and such relevant fields. However, the rocks complicated formations and properties cause large ambiguity and a lot of limitations to the recognition of the rocks inherent attribute, and as a result the research of the reservoir stresses and fractures is still at the exploratory stage.This dissertation mainly focused on the hot issues and difficult questions in the study of rocks property parameters, reservoir stress distributions and fracture characteristics, learn from the predecessors research results, and make use of modern mathematics, mechanics, and computer knowledge to propose an actual analysis and prediction technique to the stress field and reservoir fracture distribution suitable for low-permeability oil and gas reservoirs, by means of theoretical deduction, numerical simulation, case study, corresponding software development and so on.First of all, established an effective model for the acquisition of rocks parameters based on the relationship between rocks acoustic characteristics and mechanical properties, calculated the rocks property parameters in the light of core test data and optimization back analysis technique utilizing large number of conventional logging information, studied the rocks stochastic and fuzzy attribute, and obtained its statistical eigenvalues of rocks elastic modulus and Poisson’s ratio.Secondly, derived mathematical and FEM models for the reservoir stress analysis and prediction, set the magnitudes and azimuths of some key wells in Jiangsu Oilfield as the constraints, made use of multi-objective optimization techniques to obtain the distribution regulations of principal stresses, pore pressures and fracture stresses. Fit the related curves of the principal stresses versus the depths of Jiangsu Oilfield, whose results indicated that the accuracy can meet the engineering requirement.Thirdly, carried out a research on the reservoir rock stress state functions and the failure surface equations expressed by multi-strength parameters, put forward a multi-parameter model for the analysis and prediction of reservoir fractures, which can make up effectively for many defects of conventional criteria. At the same time, in order to consider the influence of rocks original defects, the dislocation theory was introduced to the reservoir fractures research, and a novel model based on dislocation theory was presented, which provided a feasible and effective method for reservoir fractures prediction. Furthermore, a stochastic finite element analysis using the Monte Carlo method was introduced into our research to study the effect of the probabilistic rocks parameters to the reservoir fractures. All our case study results show that the models in this dissertation can give out a better prediction of the fractures, and reflect the distribution of the fractures’density.Finally, a corresponding software named "Reservoir Stress and Fracture Analysis system (RSFA)" was designed, which provided an effective way for the theoretical research results applying to the actual oil production comprehensively and conveniently, and make a simple implementation of the transformation from the theoretical approach to the practical application of engineering.更多还原