涠洲12-1N油田开发储层保护技术

涠洲12-1N油田地层坍塌压力高,而地层流体又处于正常的压力梯度。地层压力系数小于1.05 g/cm3,实际使用的钻井液密度大于1.30 g/cm3,采用尾管射孔和裸眼打孔筛管完井2种完井方式。钻井液流体压力将远大于地层流体压力,其结果将导致钻井液侵入油气层深度和数量过大,极易造成储层污染和损害,生产返排压力过高等。为安全钻开油层并保护好储层,通过对涠洲12-1N油田地层情况、定向井对钻井液的特殊要求、储层物性及敏感性分析研究,阐述了如何采取正确的储层保护措施,优选并成功地使用合适的钻井液体系和完井液体系及相应的技术措施,实现了优快钻井的工程需要,有效地减轻了钻完井作业过程中可能造成的油气层损害。

Reservoir protection technology in WZ12-1N oilfield development

Caving pressure of WZ12-1N oilfield is high while the reservoir liquid has normal pressure gradient.Formation pressure coefficient is less than 1.05 g/cm3 and the drilling fluid used is bigger than 1.3 g/cm3.Two well completion systems of perforation completion and open hole completion were adopted.Because the drilling fluid pressure is higher than that of the reservoir fluid,the drilling fluid will intrude into formation deeply and quantitatively.This would cause reservoir contamination and damage as well as abnormally high flow-back pressure.Measures of properly protecting reservoir,optimizing and choosing appropriate drilling and completion fluid systems were formulated by studying the reservoir nature,sensitivity and special requirements of deviated holes in WZ12-1N oil field for drilling fluids.The goal of drilling fast and excellently was realized and the possible damage in the process of drilling was effectively alleviated.