疏松砂岩油气藏水平井管外地层砾石充填机理及模拟基础研究

Gravel-packing is a well known effective sand cnontrol and well completion technology for unconsolidated sandstone reservoir, but its application in horizontal wells is limited to inside casing and wellbore gravel-packing. In recent years, some accidental site inside casing gravel-packing operations in horizontal wells indicate that the fact of outside casing gravel-packing in horizontal wells is subsistent and it's possibile to be implemented purposively. Outside casing gravel-packing means goog sand control effect and can also decrease horizontal well skin factor and improve well productivity. This project will perform the prospective application basic research of the issue of outside casing gravel-packing in horizontal wells. In this project, on the basis of another relative NSFC project completed before, the unconsolidated sandstone rock failure mode, which may concern one of fracture initiation and extension and another of plastic compaction breaking, and its diagnosis model will be focused on. Then, aim ate the rock failure mode of plastic compaction breaking, the study on numerical and experiment simulation of outside casing gravel-packing in horizontal wells will be performed to estiablish the numerical simulation model for horizontal well outside casing gravel-packing. The above study medthods involves matematical model and experimental apparatus and consider the heterogeneity of formation rock properties and 3-D stress field anlog horizontal wellbore trajectory. Finally, the corresponding visual simulation software package will be developed to visually simulation the whole packing process and predict the final packing parttern. This project and its implementation would provide prospective foundation for the real application of outside casing gravel-packing in horizontal wells.

砾石充填这一有效的疏松砂岩油气藏防砂完井方式在水平井中的应用目前仅限于井筒或套管内充填。但近年来的一些有意无意的工程实践证明了水平井管外地层砾石充填的存在及其有目的实施的可能性。管外地层充填防砂效果好，更可贵的是可以最大程度降低完井表皮提高水平井产量。本项目将针对水平井管外地层砾石充填，开展前瞻性的应用基础理论研究。项目拟在前一项目研究基础上，考虑水平井沿井身轨迹分布的岩石特性参数及三维地应力的非均质性，通过数学模型和室内模拟实验，研究疏松砂岩水平井管外地层岩石在高压挤注条件下的破坏机理和模式（裂缝开裂延伸和塑性挤压破碎）及其判别方法；重点针对水平井管外地层塑性挤压破碎模式，开展管外地层砾石充填的实验模拟和数值模拟研究，建立复杂应力场下水平井管外地层砾石充填模拟的数学模型，开发模拟软件，模拟充填动态过程并预测最终充填结果。为管外砾石充填技术在疏松砂岩水平井中的应用提供前瞻性理论基础。

砾石充填这一有效的疏松砂岩油气藏防砂完井方式在水平井中的应用目前仅限于井筒或套管内充填。但近年来的一些有意无意的工程实践证明了水平井管外地层砾石充填的存在及其有目的实施的可能性。管外地层充填防砂效果好，更可贵的是可以最大程度降低完井表皮提高水平井产量。由于缺乏疏松砂岩油藏管外地层岩石的破坏模式及塑性挤压破碎充填过程的基础理论研究，疏松砂岩油藏水平井管外砾石充填工艺的应用尚处于探索阶段，距离其真正工业化应用还尚需时日。本项目通过基础理论研究，结合不同胶结程度地层的出砂机理和类型，创新提出了高压挤注条件下疏松砂岩岩石的塑性挤压破坏、裂缝延伸充填破坏，以及塑性挤压和裂缝复合充填三种模式，并研究建立了三种模式的判别模型和方法；基于注入过程中储层温度变化引起的瞬态应力场变化规律，研究建立了高压挤注条件下弱胶结岩石破坏机理及模式以及塑性挤压充填破坏机理及动态模拟模型与方法。在出砂形态模拟的基础上，研究了砾石充填过程模拟和充填形态和半径预测方法。研究得到的亏空地层砾石充填形态模拟技术，可模拟给定施工参数下的充填形态、有效充填半径和充填率。最终形成了疏松砂岩水平井管外管内一体化砾石充填过程数值模拟方法与技术。配合水平井管外砾石充填模拟与优化设计，研究形成了水平砾石充填井砾石层堵塞机理与规律、充填程度影响因素、充填井动态产能预测、砾石充填筛管评价等理论与方法。本项目共发表研究论文15篇，出版学术专著2部，授权发明专利2项，申请发明专利2项，获得软件著作权5项，获省部级技术发明一等奖1项，二等奖1项，培养硕士研究生5名。