BZ29-4S油田软泥页岩钻井液技术研究

Research on the Soft Shale Drilling Fluid in BZ29-4S Oilfield

针对BZ29-4S油田预探井和评价井软泥页岩地层钻井过程中起下钻不畅、起泥球现象严重、机械钻速低、钻井液流变性难以调控以及维护困难的问题,通过抑制作用机理分析,优选了NaCl作为该油田软泥页岩钻井液的抑制剂;根据泥球形成条件和形成机理,研制了一种不影响钻井液性能的防泥球剂。通过抑制剂和防泥球剂加量优选,构建了适用于BZ29-4S油田软泥页岩地层的钻井液体系。现场应用表明,该钻井液体系能够有效防止钻屑形成泥球,缩短了起下钻时间,降低了倒划眼难度,提高了机械钻速。

Aiming at the pipe trip blocking,the serious phenomena of mud ball forming,low penetration rate,the difficulty in regulating and maintaining rheological properties of drilling fluid encountered in wildcat and evaluation wells of BZ29-4S Oilfield during drilling in the soft shale formation,NaCl was optimized as the inhibitor for the soft shale formation in BZ29-4S Oilfield,through the analysis of inhibition mechanism.According to the condition and mechanism of mud ball forming,a anti-mud ball agent which would be affect the performance of drilling fluid was developed.According to the optimization of dosage amount of inhibitor and anti-mud ball agent,the drilling fluid suitable for the soft shale formation in BZ29-4S Oilfield is established.Field application shows that the drilling fluid can avoid mud ball forming,decrease the time of pipe tripping,reduce the difficulty of back reaming,raises the penetration rate.