大庆地区深部砾岩储气层钻井液损害评价

DAMAGE EVALUATION OF DRILLING FLUID ON CONGLOMERATE GAS RESERVOIR IN DEEP FORMATIONS IN DAQING

针对大庆深部砾岩储气层低孔、特低渗、非均质性强的特点,通过防膨胀低钻压切割技术、砾岩人造裂缝岩心制作技术、砾岩储气层损害评价实验和不同尺寸砾岩岩心孔、渗相关性研究,实现了在现有实验技术和设备条件下,采用标准岩样进行钻井液的模拟损害评价。解决了以标准砾岩岩心替代全直径砾岩岩心进行模拟损害评价的技术难题,并进行了大庆深部砾岩储气层钻井液损害评价。结果表明:砾岩基质和裂缝宽度在5～10μm的砾岩裂缝,水基钻井液的主要损害方式为水锁损害;裂缝宽度在20μm的砾岩裂缝,水基钻井液的主要损害方式为固相损害。

Due to the features of low porosity,extremely low permeability,and high heterogeneity of deep conglomerate gas zones in Daqing,swelling-preventive low-WOB cutting technology,preparation of artificial fractured conglomerate cores,damage evaluation experiment on conglomerate payzones,and investigation on the relationship of the porosity and the permeability of different size cores were adopted or conducted to realize simulation evaluation of drilling fluid damage on standard cores with existing experiment technology and equipment.The use of standard size cores had overcome the difficulty met by full-size cores.And the drilling fluid damage made on deep conglomerate payzones in Daqing was evaluated.The study results showed that for fractured conglomerate rocks with conglomerate matrix,the major damage by WBM will be water lock when fracture width was at 5-10 μm and will be solids damage when fracture width was about 20 μm.