【作者】 梁利喜；

【导师】 许强；

【作者基本信息】 成都理工大学 ， 地质工程， 2008， 博士

【摘要】 地应力场的正确评价是地下深部工程安全、合理、高效实施的基础。在石油工程领域,深部地应力研究是油气勘探开发的前期工程和基础工作,对推动油气勘探开发技术理论的发展、提高整体经济效益有着重要作用。本文以塔河油田为例,综合利用油气地质、地震勘探、石油工程测井及增产压裂等油气勘探开发相关资料,在深入分析地质构造、深部地质环境(孔隙压力、地层温度)、结构面发育分布以及深部地层岩石力学性能的基础上,较为系统地研究了深部应力场特征,并开展了油气井井壁失稳分析研究。取得的主要成果及认识如下:(1)综合利用岩心观察、成像测井识别等手段重点描述、评价了奥陶系地层裂缝的发育特征。结果表明:裂缝走向以北东65°～75°和32°～43°为主,次为274°～292°;倾角以高角度占优;裂缝的发育程度主要受控于构造轴部、构造高点以及断裂分布,此外地层的岩性、埋深对裂缝发育的影响也较为显著。(2)在深入分析纵波速度模型的基础上,通过引入地层体积密度,改进了地层孔隙压力测井综合解释方法。结合实测数据利用该方法对研究工区的地层孔隙压力进行了分析评价,结果表明:塔河油田地层孔隙压力系数为0.80～1.35,平均1.10左右,属于正常压力系统;并且随地层埋深增大,总体呈增大趋势。(3)在区域地温分析的基础上,基于实测数据研究了工区的地层温度分布特征,结果表明:工区地温梯度为1.91～2.73℃/m,属偏低地温系统;随地层埋深的增大,地温梯度呈现明显的线性减小趋势;在平面上,平均地温梯度呈现东部高,西部低的分布特征。(4)通过系统分析钻井循环过程中地层、钻柱液体、环空液体之间的换热机制,依据能量平衡及传热学相关理论建立了井壁温度场分析模型。应用该模型分析了钻井循环过程中井壁温度的分布特征,具体表现为同温点之下各深度点井壁温度低于原始地层温度,同温点上部则相反,井底处井壁温度降低幅度最大;并研究了循环时间、地温梯度、地层热传导率以及井深对井壁温度分布的影响。(5)综合利用岩石力学试验测试及石油工程测井分析两种技术手段,研究了深部地层岩石不同围压、温度条件下的变形破坏特征;基于石油工程测井计算分析结果,研究评价了工区地层岩石力学参数的空间分布特征,结果表明:纵向上,随地层埋深的增大、地层岩石力学参数总体增大趋势明显;平面上,地层岩石的弹性模量、抗压强度总体表现出北高南低的分布特征。(6)在区域应力分析的基础上,综合应用人工裂缝实时检测、钻井诱导缝分析以及井壁崩落分析三种技术手段对研究工区的深部应力场方向进行了系统分析研究。研究工区现今应力场主要受控于区域应力构造作用,水平最大主应力优势方向为NE40°～NE65°。(7)导出了不同完井方式下的水平最大主应力反演计算模型,完善了基于油气井增产压裂资料反演分析深部地应力的系统方法体系;15口井的增产压裂资料分析表明:在研究工区分析深度范围(5440～6100m)内,水平最大主应力大小为108.0～129.0MPa;水平最小主应力为77.0～107.0MPa;分析井段深度三个主应力的大小关系为σ_v≥σ_H≥σ_h,属潜在正断型应力场。(8)探讨了有限单元法结合人工神经网络实现深部地应力场反演的基本理论思想,建立了综合应用有限单元与人工神经网络方法进行深部地应力场反演分析的研究思路及技术流程。并应用该理论方法分别以不同尺度范围对研究工区地应力场进行了二维、三维数值模拟反演分析。(9)对深部地层井壁的力学失稳进行了分析研究:(a)系统归纳了常见井壁失稳的力学模式,并分析了各失稳模式的井周易发方位以及与钻井液密度的关系;(b)构建了完整井眼及结构面发育井眼的井壁力学失稳定量评价指数;分析了原地应力状态、地层温度扰动、地层孔隙压力、结构面发育以及井眼轨迹对井壁力学失稳的影响;(c)改进优化了现有的维持井壁稳定的钻井液安全密度评价方法及计算模型,弥补了常规方法仅靠某一种或两种失稳模式确定安全钻井液密度的不足,结果更合理、可靠。(10)通过分析认为:层位埋深大、构造应力作用强、结构面发育以及局部地层岩石力学性能差是导致塔河油田井壁失稳的主要内因;在地应力场三维数值模拟反演、岩石力学参数空间分布分析的基础上,区域性地计算分析了安全钻井液密度,为保持井壁稳定的钻井工程设计提供了参考。更多还原

【Abstract】 The accurate evaluation of deep in-situ stress is the base of the safety,high efficiency of underground engineering.In the field of petroleum engineering,the evaluation of the in-situ stress is very important for development the theory of exploration and exploitation and raise economic benefits.In this paper,taken TaHe oil field for instance,with oil and gas exploration and exploitation data,basing on the analyses of the geological structure,deep geological environment(formation pore pressure,formation temperature),structural plane and the mechanical properties of deep rock,deep in-situ stress field was studied systematically and the wellbore satiability of oil well was analyzed,the main results are as follows:(1)Utilizing core identification and image logging analyses,the growth characteristic of fracture was been evaluated.The result indicated that:for the most fracture,the orientation is 65°～75°and 275°～295°,and the dip is high;The fracture development is mainly controlled by structure axis,structure high spot and faults.In addition,the lithology and depth of formation have significant effect on the fracture development.(2)On the base of analyses P-wave velocity modeling,formation bulk density is been considered.The Logging Integrated Evaluation Model for formation pressure had been improvement.Combined to measure data,the pore pressure in TaHe oil field was been evaluated by this model.The result shows that the formation pressure coefficient is about 0.80～1.35,belong to normal pressure system and become large with the depth increasing.(3)In the TaHe oil field shows that the geothermal gradient is about 0.0191～0.0273℃/m,Slightly higher than the average geothermal gradient of the Tarim basin,and lower than China’s other large and sedimentary basin,is lower geothermal system.(4)Through the analyses heat exchange mechanism along the formation,drill sting liquid,annular liquid during the drill circulation,basing on the energy balance and the heat transfer theory,the wellbore temperature field model has been set up.The borehole temperature distribution has been analyzed during drill circulation by using this model.The analysis result indicated that there is a depth where the formation temperature of the borehole and the formation temperature is the same.Under this depth,the borehole temperature is lower than the original formation temperature,and it is opposite upside this depth.At the well bottom,the welbore temperature reduces the scope to be biggest.The impact of circulation time,geothermal gradient,the stratum heat conductivity as well as the well depth over the wellbore temperature distribution and the maximal perturbation temperature has been studied.(5)Using the rock mechanics test and the petroleum engineering logging analysis, the deep rock deformation and failure characteristics has been studied under the condition of the different pressure and temperature.Further,basing on logging analysis,the spatial distribution of rock mechanics parameter has been studied.(6)In the region stress analysis’s foundation,the deep stress direction has been carried out studies systematically,through the analysis of the real-time detection of artificial fracture,drill-induced fracture and wellbore breakouts.The studied results shows that in the research region,modern stress field is controlled mainly by regional tectonic stress,and the maximum principal stress directions is NE40°～NE65°.(7)The Horizontal biggest principal stress inversion computation model has been derived under the different well completion condition.Using this model,fracturing data for stimulation has been analyzed in the 15 wells,the result show that the magnitude of the maximum principal stress is 108.0～129.0Mpa and the magnitude of the minimum principal stress is 77.0～107.0Mpa where the depth is 5440～6100m. The order of three principal stress magnitudes isσ_v≥σ_H≥σ_h·(8)The basic theory has been discussed that utilizing the finite element method with artificial neural network to inverse deep stress field.And the research thinking and technique process has been established.Using this theory and way,numerical simulation inversion analysis of the 2D and 3D stress field in the research region was been done in different scale.(9)The mechanical instability of deep wellbore was analyzed.(a)The common mechanical mode of wellbore instability was been summed up systematically,and the relation between mechanical mode of wellbore instability and the density of drilling fluid,the wellbore azimuth has been analyzed.(b)The quantity evaluation index of wellbore mechanical instability has been established.It was analyzed that In-situ stress state,formation temperature perturbation,formation pressure,week plane and well trajectory affect on wellbore instability using the index.(c)Existing evaluation method and calculation model of drilling fluid density that maintains wellbore stability has been improvement,the result is more reasonable and reliable.(10)Primary factor that induce wellbore instability has been analyzed.And the drilling fluid density,which maintains wellbore mechanics stability,was been calculated.It provides the important reference for drilling engineering design.更多还原