潮控河口湾油砂储层构型及盖层完整性评价研究

Oil sands is one kind of resource with shallow buried depth, being loose, good physical property, high heterogeneity, thin caprock especially the reservoir of the internal interlayer, thus the distribution of the configuration interface has a great influence on the regular expansion of the thermal recovery steam chamber, and a thin caprock can ensure the integrity in the process of thermal recovery, which can assure safety production and environmental requirements. The studies both at home and abroad show that on the one hand that most of current SAGD Projects aim at the meandering river sedimentary reservoir affected by the tide, but few of them turn to the tidal estuary reservoir and there is no successful development experience, as a result, the influence of internal configuration interface of the tidal estuary on the development of thermal recovery is not definite. On the other hand, there are few studies on the integrity mechanism of the caprock in the process of SAGD Project of oil sand, so it is urgent to carry out related researches, forming a reliable evaluation technology . This project plans to take the MacKay River oil sand block, PetroChina branch in Canada, as an example to start the study on the configuration of tidal estuary reservoir and integrity mechanism of the caprock in the condition of high temperature and high pressure, aiming to form integrated research methods and lay a geological basis for the efficient development of the project. And this project will provide guidance for the effective development of the oil sands project in Canada by using SAGD and the safety production of other projects around.

油砂储层埋藏浅，疏松，物性好，非均质性强，上覆盖层厚度较薄，导致储层内部构型界面对蒸汽腔的扩展影响至关重要，而热采过程中盖层的完整性则关系到油砂安全生产。本项目拟以中石油加拿大麦凯河油砂区块作为研究对象，在层序地层学、沉积体系、储层反演研究搞清油砂发育、分布的基础上，通过对砂体内部构型的剖析，认识沉积界面的发育、分布规律及其对SAGD开发的影响，结合构造、储盖组合及SAGD过程中盖层完整性机理的分析，明确有利储盖发育区域，形成一体化研究方法。本项目的研究将为麦凯河油砂区块的高效开发奠定地质基础，并对海外油砂项目的SAGD高效开发提供基础保障。

项目围绕“加拿大麦凯河油砂区块SAGD开发过程中油砂储层分类、储层内夹层分布及热采开发过程中盖层分布及完整性”这一目标，以“整体部署、分步实施、科研攻关与现场支持并重”为原则，开展研究工作。通过四年的攻关研究，明确了油砂区块地质特征，探索了麦凯河油砂储层分类方法，表征了砂体和隔夹层空间分布，开展了SAGD开发过程中盖层完整性评价，为确定合理开发方式奠定地质基础。具体取得了以下几点认识与成果：. 1.研究区油砂资源目的层麦克默里（MCMR）上段地层由加积至进积准层序组和退积准层序组两个沉积准层序组组成，最初沉积在一个潮控至受潮汐和波浪共同影响的港湾中，砂体纯净且连续性好，砂体在不断加积和进积作用下平面上形成线性潮汐砂坝，纵向上若干单一砂坝叠置组成的潮汐砂坝集合体呈现典型的反旋回。随着海平面的不断升高以及沉积物供给的逐渐减少导致沉积环境由海陆过渡相逐渐向海相沉积环境转变。. 2.以岩心观察描述为基础，在等时格架内开展潮汐三角洲储层单砂体空间构型研究。将研究区岩相划分为交错层理砂岩相，平行层理砂岩相，生物扰动砂岩相，压扁层状砂岩相，波纹层状砂岩相，生物扰动泥质砂岩相等13种类型。岩石组合形成了河道、砂底形，顺流加积的大型底形，侧向加积沉积和纹层砂席等几种单元。. 3.应用岩心和测井资料，结合沉积微相、岩石相和流体分布，分基于不确定性分析构造框架建模、基于沉积相控制岩石相建模、基于岩石相控制储层参数建模，基于界面控制流体属性建模四步建立的三维精细模型更加精确可靠。并基于地质模型计算了适用SAGD开发方式的地质资源量。. 4.分析了SAGD开发过程中盖层的岩石学参数、力学参数、热力学参数，对各影响因素进行了归一化处理的基础上，运用AHP层次分析法确定了各主控因素的权重，建立了SAGD开发过程中盖层完整性评价模型，在此基础上得出盖层完整性评价分区，并根据分区提出了相应的防破裂建议。