非渗透钻井液在渤930井泥岩裂缝易塌地层的应用

为了解决渤930井三开中生界和古生界地层硬脆性泥岩易剥蚀掉块、垮塌等问题,研制了非渗透钻井液体系。对该区块中生界、古生界复杂泥页岩地层的井壁不稳定问题进行了分析,找出了该地层坍塌的主要原因是由于伊利石水化膜厚、水化斥力大、裂缝发育引起的。针对该技术难点进行了分析,研制了非渗透乳化钻井液体系配方,该配方通过在钻井液中加入了由一系列可溶于油和水的改性聚合物混合而成的油层保护材料FLC2000,强化防塌措施。针对不同地层,制定了不同的钻井液维护要点。现场应用表明,三开选用的非渗透钻井液体系能快速形成渗透率很低的封堵层,阻止流体进入微裂缝,有效防止该地区泥岩裂缝地层坍塌掉块。非渗透钻井液成功解决了该区块的坍塌掉块问题,可进一步在该区块推广应用。

NON-INVASIVE DRILLING FLUID UTILIZATIATION IN SLOUGHING SHALE FORMATION WITH CRACKS OF WELL BO930

To deal with the scaling and sloughing of rigid and fragile shale in Mesozoic and Palaeozoic group of Well Bo 930,the non-invasive drilling fluid was selected.The borehole instability problems of Mesozoic and Palaeozoic group in this area have been analyzed,and main reasons of formation sloughing was founded which are caused by thick illites hydration shell,great hydration repulsion,and abundance in cracks.The formulation of non-invasive drilling fluid was developed,and through adding non-invasive additives which is a mixture of a series of oil-soluble and water-soluble modified polymer,anti-sloughing measures can be strengthened.Different maintenance outlines have been made according different formations.Field application shows that the non-invasive drilling fluid system used in tertiary drilling can rapidly form plugged zone with ultra low permeability and prevent fluid pressure enterring into formation,so as to prevent crack shale formation sloughing and scaling of this area.The probleums of sloughing and scaling of this area has been solved successfully through the utilization of non-invasive drilling fluid,so this drilling fluid can be popularized in this area furthermore.