沙特B区块致密砂岩气层保护技术研究

PROTECTION TECHNOLOGY OF TIGHT GAS RESERVOIR IN SAUDI ARABIA BLOCKS B

沙特B区块SAHRA储层孔隙度、渗透率低,平均孔喉中值半径小于0.1μm,属于典型的致密砂岩气层。认清储层损害机理,设计合理的保护储层的钻井液体系是致密砂岩气藏高效开发的前提。敏感性实验研究结果表明,该储层存在中等偏弱速敏、中等偏弱的水敏和盐敏、以及弱的酸敏和碱敏,水锁程度为中等。针对储层损害特征,选用抗温、低滤失的无黏土KCl钻井液体系,为减轻水锁伤害,在钻井液体系中加入SPAN-80。室内实验结果表明,钻井液污染岩心后气测返排渗透率恢复值可达到75%以上。现场应用储层保护效果良好,ATNB-2井SARHA储层表皮系数为-2。

The SAHRA reservoir in B block of Saudi Arabia has very low porosity and permeability,it belongs to typical tight sandstone gas reservoir with average Median radius of pore throat less than 0.1μm.Results of sensitivity experiments showed that the reservoir has the characters of Medium weak speed-sensitive,water sensitivity and salt sensitivity,as well as a weak acid sensitivity and alkali sensitivity,Aqueous trapping damage is moderate.In view of characteristics of reservoir damage,the KCl drilling fluid system has been used,which is without clay,and has the characters of low filtration and anti-high temperature,and SPAN-80 has been added in drilling fluid for decreasing water lock damage.Experimental results showed that recovery of permeability tested with gas could reach 75% after cores were contaminated by drilling fluid.Field application effect of the reservoir protection technology is good,the skin factor of ATNB-2 in SARHA reservoir is only-2.