一种高效清除井壁滤饼的新型固井冲洗液

为有效清除水基钻井液滤饼，提高固井界面胶结强度和固井质量，基于水溶性纤维的强冲刷原理和滤饼氧化分解原理，研究出一种新型的固井冲洗液（WD-C） ：0.5%WF-H纤维+2.2%WF-O氧化剂+0.35%FeSO₄ +1.8%KCl+3.0%膨胀珍珠岩粉+水，密度为1.03 g/cm³。为此，系统地测试评价了该冲洗液对水基钻井液滤饼的清洗效率和改善固井界面胶结强度的性能，并通过红外光谱（IR）、扫描电镜（SEM）和元素分析（EDS）等方法分析了其对界面胶结物的理化特征和微观结构的影响。结果表明，该冲洗液对水基钻井液滤饼具有良好的冲洗作用（冲洗干净时间在10 min内），且界面胶结处的水泥颗粒能够正常水化，生成水化硅酸钙凝胶、Ca（OH）₂和棒状钙矾石（AFt）晶体，并相互交织并形成致密网络结构，能显著提高固井二界面胶结强度，进而提高固井质量。该研究成果为解决高效快速清除水基钻井液滤饼、提高固井二界面胶结强度技术难题提供了又一种新的技术方法。

A new cementation flushing fluid for efficiently removing wellbore filter cake

For effectively removing the water-based drilling fluid filter cake and improving interfacial cementation strength and cementing quality, a new type of cementation flushing fluid (WD-C) was developed based on the strong flushing principle of water soluble fiber and the oxygenolysis principle of filter cake. It is composed of 0.5% WF-H fiber, 2.2% WF-O oxidant, 0.35% FeSO₄, 1.8% KCl , 3.0% swollen powder perlite and water with its density of 1.03 g/cm³. This cementation flushing fluid was systematically tested and evaluated in terms of its washing efficiency on the filter cake of water-based drilling fluid and its capacity to improve the bonding strength of cementation interface. In addition, an analysis was performed of its effect on the physical-chemical characteristics and the micro-structures of interfacial cements by means of infrared spectrum (IR), scanning electron microscope (SEM) and energy dispersive X-ray detector (EDS). It is shown that the new cementation flushing fluid presents excellent washing effect on water-based drilling fluid filter cake (with washing time within 10 min). The cement particles at the cemented interface can be hydrated normally, and hydrated calcium silicate gel, Ca(OH)₂ and rod-shaped ettringite (AFt) crystal are generated and interwoven with each other. In this way, dense network structures are formed, so the bonding strength of the second cementing interface rises significantly, and then cementing quality is improved. Based on the research results, one more technology is set up for removing the water-based drilling fluid filter cake efficiently and improving the bonding strength of the second cementing interface.