强分散性地层大位移井钻井液关键技术研究

Study on key technologies of ERD well drilling fluid in highly dispersed formation

海外K油田计划从湖岸钻大斜度井及大位移井开发,区域地层胶结疏松、蒙脱石类黏土矿物含量高易水化膨胀,探井井下复杂事故频发,未来开发井钻井面临井壁失稳垮塌、大位移井摩阻扭矩大、“零”排放的环保要求等难题。从地层理化性质分析入手,揭示该区大位移井钻井液主要技术要求,通过理论分析与实验研究相结合形成适合该区强分散性易垮塌地层大位移井钻井的合成基钻井液技术。推荐的合成基钻井液密度1.2~1.4 g/cm^(3),回收率大于90%,高温高压膨胀率低于1.5%,中等-强的抗岩屑污染能力,浸泡后岩石强度比水基钻井液同等条件下高60%,稳定井壁效果好,润滑性能良好,对储层损害小,可重复使用,产生的钻井废弃物量减小59%。该技术是成功实施湖岸大位移井钻井的重要保障,也为实现该油田安全环保经济高效开发奠定了坚实基础。

The K oilfield plans to drill ERD wells from the lakeshore wellpads.The regional formation has loose cementation,high content of montmorillonite clay minerals,easy hydration and expansion,and downhole accidents of exploration wells occur frequently.The drilling of development wells will face problems such as wellbore instability,large friction torque of ERD wells,and local stringent environmental requirements.Starting with the analysis of the physical and chemical properties of the stratum,this paper reveals the main technical requirements of the drilling fluid for ERD wells in this area,and forms a synthetic based drilling fluid technology,which is suitable for the drilling of ERD wells in highly dispersed and collapsible formations in this area.The recommended SBM has a density of 1.2~1.4 g/cm^(3),a recovery rate of more than 90%,a HTHP expansion rate of less than 1.5%,a medium strong resistance to cuttings pollution,an UCS 60%higher than that of WBM under the same conditions after immersion with mud,good lubrication performance,little damage to the reservoir,can be reused,and the amount of drilling waste can be reduced by 59%.This technology is an important guarantee for the successful implementation of lakeshore ERD drilling,and also lays a solid foundation for the safe,environmental,economic and efficient development of the oilfield.