四川盆地侏罗系沙溪庙组含浊沸石砂岩储层特征及其油层改造建议

Reservoir characteristics of the laumontite sandstone of Jurassic Shaximiao Formation in Sichuan Basin and some suggestions on improving the reservoir

四川盆地侏罗系沙溪庙组砂岩储层存在着十分严重的储层损害潜在因素,在钻井和油层改造过程中及易造成油层伤害.通过对川中地区沙溪庙组砂岩储层微观地质特征和储层潜在损害因素的分析,结合陕北安塞油田长6油层地质特征和近20a的酸化压裂技术方法,建议在下沙溪庙组油层酸化压裂改造过程中使用田菁粉压裂液,在压裂液的反排时采用“控制反排速度,逐步放大压差,压裂末期适当挤入少量大直径压裂砂”,以避免砂粒受冲击造成地层伤害;建议酸化液添加冰醋酸稳定剂,或其他一些铁离子络合剂,并尽可能缩短工期,避免形成沉淀堵塞孔喉;对于含浊沸石的砂岩储层,不宜用盐酸酸化,建议用酸度较弱的磷酸或磷酸与盐酸的混合酸.

The Jurassic Shaximiao sandstone reservoir has serious pot ential reser voir damage factors, and they easily lead to reservoir damage during drilling an d reservoir improving. Based on the analyses of the potential reservoir damage f actors and the microscopic geologic features of the reservoir, several suggestio ns are proposed for the improvement of the reservoir: sesbania gum fracturing fl uid should be used in acidizing-fracturing process and the best way of fracturi n g fluid return is controlling return flow speed, slowly increasing pressure diff erence, and squeezing some coarse sand into reservoir in the end of fracturing p rocess in order to prevent sand particles leading to reservoir damage; acetic ac id or ferric ion complexing agent should be added in acidizing fluid and the tim e of acidizing-fracturing process should be as shorter as possible for avoiding sedment plugging pore throads; phosphoric acid or the mixing acid of phosphoric acid with hydrochloric acid should be used for the laumontite sandstone reservoi r.