钻井液漏失动力学机制及防漏堵漏技术应用基础研究

As the conventional oil and gas resource decrease day by day, oil and gas development have to extend to deep reservoir, and the deep fractured carbonate reservoir has become a significant part of oil and gas development. This kind of reservoir has a complex geologic feature, such as deep burying, high temperature and pressure and fracture development. It's easy to occur serious drilling fluid (mud) loss during drilling, so the drilling fluid (mud) loss mechanism and leak resistance and sealing technology research appear to very necessary. The base of leak resistance and sealing technology for fracture carbonate reservoir is loss feature and loss dynamic mechanics analysis. We have founded a comprehensive experiment platform base on the results of previous studies which can realize wellhole and reservoir condition simulation to carry out effectiveness evaluation of "leak resistance and sealing technology" of drilling fluid (mud) system, and also, we studied the experiment evaluation standard. We carry out pressure-bearing and leak resistance experiment to analysis material feature under the condition of high pressure, high temperature and wellbore circulating status; We use FEM simulation technology to forecast fracture width dynamitic change and drilling fluid (mud) loss under 3D fluid-solid coupling condition; We set up relevant comprehensive mathematics model based on drilling fluid (mud) loss Kinetics law. It's significance to study fracture reservoir drilling fluid (mud) loss mechanism and leak resistance and sealing technology.

随着常规石油与天然气资源量的日益减少，油气开发活动越来越向深部储层发展，深层裂缝性碳酸盐岩储层已成为油气开发活动的重要场所，此类储层具有埋藏深、温度压力高、裂缝发育等复杂工程地质特征，钻井过程中具有工作液漏失严重的现象，因此对钻井液漏失机理及防漏堵漏技术研究显得十分必要。裂缝性碳酸盐岩储层漏失特征和漏失动力学机制研究是防漏堵漏技术基础。在前人研究成果基础上已初步建立了一套能实现模拟井筒、地层条件进行"暂堵堵漏"钻井液体系效果评价的综合实验平台，并探索了相应的实验评价标准。拟通过开展承压堵漏实验，分析堵漏材料体系在高温高压、井筒循环状态的漏失等特征；应用有限元数值模拟技术对三维流固耦合条件下的裂缝动态宽度变化和钻井液漏失规律进行预测；根据钻井液漏失的动力学参数特征建立相应综合数学模型。项目研究对裂缝储层钻井液漏失机理和防漏堵漏措施具有重要的指导意义。

随着我国油气勘探开发步伐的加快，裂缝性油气资源的勘探开发越来越受到人们的重视，钻井液的大量漏失不但会影响正常钻进，还可能引发严重的井喷事故，若漏失发生在储层段，钻井液液相进入油气层会对储层造成严重的伤害。裂缝性地层钻井液漏失成为制约裂缝性油气资源高效开发的技术难点之一。.课题以裂缝性地层为研究对象，在前人研究的基础上，通过开展室内裂缝宽度模拟实验、流-固耦合裂缝宽度变化计算机仿真模拟及建立井漏资料预测漏失裂缝宽度数学模型等手段综合研究工区漏失地层漏失裂缝宽度变化机理，为现场防漏堵漏设计提供更加可靠的预测方法及设计依据；根据现场漏失资料及漏失原理，以静态缝宽计算模型为基础，对现有的漏失裂缝宽度预测模型进行了修正，建立了修正后漏失裂缝宽度预测数学模型，并根据现场漏失资料计算了漏失裂缝宽度范围。.基于建立的裂缝宽度预测模型，提出了储层结垢暂堵堵漏方法，利用纤维材料作为架桥物质对裂缝形成初次封堵，再以化学方法生成结垢物，其充当了填料和可变性微粒的作用，充填和吸附在纤维材料中，从而加强封堵层；基于化学反应动力学原理，通过设计碱液-岩石反应动力学实验，分析碱液浓度、反应温度等对反应速率的影响，构建反应动力学和活化能模型，系统描述了碱液-岩石反应动力学行为，为进一步明确碱液侵蚀岩石机理提供理论支撑；基于漏失裂缝宽度预测模型及堵漏钻井液的研究，提出了裂缝性地层井筒强化、裂缝封堵的新工艺及新方法，并在四川盆地东北部HB油田得到成功证实。