XX-1-B32超低压井钻井液技术研究与应用

Research and application of drilling fluid technology in XX-1-B32 ultra-low pressure well

超低压、多套压复杂井段结构的存在是影响老井改造和调整的难点。XX-1-B32井是位于南海北部湾海区的一口调整井,目的层涠洲组四段,该井属于压力衰竭储层,具有超低压、多套压力存在于同一井段的特点。为达到漏失预防与储层保护目的,基于地层特征参数与井段钻井风险分析,展开了钻井液室内优化试验研究,优选出了一套PDF-PLUS/KCl钻井液体系,并对其进行了性能评价。研究结果表明,该钻井液体系的流变性能稳定,高温高压失水量仅为8.2mL,26MPa压差下24h滤失量仅为10mL左右,XX-1油田岩心污染段截取0.5cm后渗透率恢复值达85%以上,其储层保护效果和封堵能力较好。该体系在XX-1-B32井进行了推广试用,现场反馈井眼净化效果好,渗透率恢复值高;最大井底压差高达35MPa时未发生漏失,泥饼承压能力强。该钻井液体系的成功应用为北部湾实施类似超低压井钻井液技术提供了较好的指导意义。

The existence of complex well section structure with ultra-low pressure and multiple sets of pressures is the difficulty affecting the reconstruction and adjustment of old wells.Well XX-1-B32 is an adjustment well located in the Beibu Gulf area of the South China Sea.The target layer is the fourth member of Weizhou Formation.The well is a pressure-depleted reservoir with ultra-low pressure and multiple sets of pressures in the same well section.In order to achieve the purpose of loss prevention and reservoir protection,based on the formation characteristic parameters and drilling risk analysis of well section,the laboratory optimization test of drilling fluid was carried out,and a set of PDF-PlUS/KC1 drilling fluid system was optimized and its performance was evaluated.The research results show that the rheological performance of the drilling fluid system is stable,the fluid loss at high temperature and high pressure is only 8.2mL,and the 24-hour filtration loss under 26MPa differential pressure is only about 10mL.The permeability recovery value of core contaminated section of XX-1 oilfield after intercepting 0.5cm is more than 85%,and its reservoir protection effect and plugging ability are good.The system has been applied in well XX-1-B32,and the on-site feedback shows that the borehole purification effect is good and the permeability recovery value is high;No leakage occurs when the maximum bottom hole pressure difference is as high as 35MPa,and the mud cake has a strong pressure-bearing capacity.The successful application of this drilling fluid system provides a good guiding significance for the implementation of similar ultra-low pressure well drilling fluid technology in Beibu Gulf.