硝酸钙胺基聚合物钻井液技术

厄瓜多尔东南部区块地层属于海相沉积,地层新,欠压实,成岩性差,吸水性强,分散度高,造浆严重,尤其是上部CHALCANA和ORTEGUAZA地层存在大段泥质含量在80%以上的泥页岩和间歇性掺杂有煤层,易出现垮塌和缩径,导致井下情况复杂。针对上述技术难题,优选出一种适合于该区块表层大井眼井段安全钻进的硝酸钙胺基聚合物钻井液体系。室内评价显示,该体系性能稳定,抑制性好,16 h泥岩岩心膨胀量只有0.47 mm,岩屑一次回收率高达96%,二次回收率为88%,固相容量高,抗污染能力强,能抗6%黏土污染或8%的钻屑污染,对钻具腐蚀性小(腐蚀速率为0.058 5 mm/a),无毒易降解。目前该钻井液体系在该区块Tapir井场进行了现场试验应用。应用结果表明,该钻井液体系防塌抑制性强,井眼净化和携砂能力良好,润滑降摩阻作用好,尤其是防泥包效果显著,起下钻畅通,φ339.7 mm套管下入一次成功率100%,保证了井壁稳定和井下安全,缩短了钻井周期。 

Calcium Nitrate Treated Polyamine Drilling Fluid Technology

In the marine sedimentary area in southeast Ecuador,formations drilled are young,unconsolidated,ready-to-disperse and highly mud making,especially theChalcanaand Orteguaza layers,where long sections of formations with more than 80% shales and with interbeded coal seams are found.These formations,having poor diagenetic grade and strong water absorption capacity,are very unstable and downhole troubles have long been encountered during drilling operations.A calcium nitrate treated polyamine drilling fluid has been engineered to drill these formations.This drilling fluid has stable properties and strong inhibitive capacity,and the rate of linear expansion of shale cores is only 0.47 mm after immersing 16 h in the drilling fluid,and the primary recovery of shale cuttings on hot rolling test is 96%,the secondary recovery of shale cuttings 88%.Tolerance to clay contamination is 6% and tolerance to cuttings contamination is 8%.This drilling fluid has low corrosion to drilling tools (corrosion rate is 0.058,5 mm/a),and is non-toxic and easy to degrade.Field application has demonstrated that this drilling fluid is highly inhibitive,has good hole cleaning capacity and cuttings carrying capacity.Good lubricity of the drilling fluid helped minimize bit balling.Borehole stabilization and safe drilling have been realized,and drilling time saved.The running of φ339.7 mm casing string has been completely successful.