【作者】 王志刚；

【导师】 闫相祯；

【作者基本信息】 中国石油大学 ， 机械设计及理论， 2009， 博士

【摘要】 油藏地应力对油气资源的形成、运移及储集等有直接控制作用,同时又是套管损坏的主要因素。研究储层的地应力特征及套管损坏机理对油田开发有重要的工程指导作用。首先,基于多目标优化技术建立了优化反分析数学模型,利用声波测井、水力压裂、裂缝监测等资料确定关键井点处的地应力大小和方位,将其做为约束,对L112区块及纯梁区块油田的地应力场进行多目标优化反分析,获取了水平主应力沿储层平面的分布规律,得到了L112区块及纯梁油田不同深度处水平主应力沿深度的变化规律。其次,提出了基于变形资料确定套管外载的位移反分析方法。通过对套管内壁部分位移的优化反分析求出套管所受的内压及外载大小,为研究套管在非均匀载荷作用下的挤毁问题和套管损坏防治措施提供了依据。再次,通过大量油田套损资料统计,分析了套管损坏的主要类型和成因,得到了典型载荷对套管损坏的作用机理和影响规律;利用有限元数值模拟技术研究了非均匀地应力对套管强度的影响,研究结果表明:在非均匀地应力作用下,无论套管还是水泥环,其有效应力及位移分布都受地应力非均匀性影响而具有各向异性,并且随非均匀系数的增加有效应力集中系数均有不同程度的增大。同时,针对N80和P110两种钢级、4种规格的套管,应用数值模拟方法,建立射孔参数的优化设计模型,得出了射孔对套管强度的影响规律,并获取了非均匀外压条件下的射孔段套管应力分布情况及不同规格套管在不同内外压作用下的应力分布规律。最后,根据前述研究成果,开展了基于地应力的套管设计方法研究,提出了“等效破坏载荷”的概念,并根据弹性力学理论,建立了套管在非均匀载荷作用下的力学模型,对理想圆管抗挤强度计算公式进行修正,得出符合套管实际承载特征的计算公式。更多还原

【Abstract】 Reservoir stress has an important effect on hydrocarbon migration and accumulation, which is also the main factor of casing damage. The study of stress characteristic and casing damage mechanism perform a guiding significance in oil andgas engineering.Firstly, the mathematical model based on multi-objective optimization technique was established to analyze the distribution of reservoir stress. Employed the sonic logging, hydraulic fracturing data and fracture detection information to calculate the principal stresses in typical wells. And then set the typical wells’ in-situ stresses of L112 block as the constraints, and utilze the optimization back-analysis technique to study the reservior stresses. The distribution of ground stresses and the curves of three-dimensional principal stresses with depth for L112 block and Chunliang oilfield were obtained.Secondly, a displacement back-analysis method based on deformation data was put forward to calculate the casing loads. Retrieved the casing loads, making use of casing inwall displacements, which provided the research basis for casing deformation under non-uniform loading and prevention measures for casing collapse.Thirdly, the mechanisms of casing failure and its influences of various typical loads were studied based on the obtained research achievement and data collection. And the effects of non-uniform loadings on casing strength was investigated by means of FEM numerical simulation, whose results showed that the distribution of effective stresses and displacements were seriously affected by the non-uniform stresses, and both the casing pipe and the cement sheath presented obvious anisotropic properties. What’s more, with the increase of heterogeneous coefficient of in-situ stress, the effective stresses concentration factors have different growth.Forthly, established the optimization design model for perforating casing using numerical simulation, and studied the stress distribution of perforated casing under non-uniform external pressure, by the research of casing strength for N80 and P110 pipes. Finally, carried out the research on casing design method based on in-situ stresses, put forward the concept of equivalent collapse resistance, and established the casing mechanical models under non-uniform loads, which has modified the calculation formula of ideal pipe collapsing strength, and abtained the formula of the actual casing pipe.更多还原