超低渗砂岩储层钻井液损害机理研究分析及解决方法---以库车北部构造带吐格尔明段为例

超低渗储层物性较差,在钻井过程中极易发生损害,致使储层渗透率下降。为深入剖析超低渗储层的钻井液损害情况,以塔里木油田吐格尔明段超低渗储层位研究对象,进行了钻井液损害机理的研究以及解决方案的设计。该层段钻井液损害值在54%~64%左右,对储层伤害较为严重。将钻井液损害细分为固相损害和液相损害两种方式,采用了扫描电镜对污染端岩心切片进行比较观测,利用恒速压汞等手段方法定性定量分析不同损害类型对储层的影响的程度。结果表明：液相侵入为主要损害方式,所占比重约80%,固相侵入为次要损害方式,所占比重约20%。测定了固相侵入深度约为25~30mm。设计对照实验,提出了添加胶束封堵剂HSM、抑制剂HAS以及防水锁剂HAR-D等措施来解决液相侵入损害的问题,发现滤液损害降低了20%,水敏损害降低60%,水锁损害降低40%以上,数据证明了所提出的方案能够有效的降低钻井液对超低渗储层的伤害。

Mechanism Analysis and Solutions of Drilling Fluid Damage Mechanism in Ultra-low Permeability Sandstone ReservoirTaking Tugelming Section of the Northern Kuqa Tectonic Belt as an Example

Ultra-low permeability reservoirs have poor physical properties and are easy to be damaged during drilling, resulting in a decline in reservoir permeability. In order to deeply analyze the damage of drilling fluid in ultra-low permeability reservoirs, the mechanism of drilling fluid damage and the design of solutions are studied based on the study of the ultra-low permeability reservoir in Tugelming section of Tarim Oilfield.. The damage value of drilling fluid in this interval ranges from 54% to 64%, which is more serious to reservoir damage. Drilling fluid damage is divided into solid damage and liquid damage. Scanning electron microscopy (SEM) is used to compare and observe core slices at polluted end. Constant velocity mercury injection (CVP) and other methods are used to qualitatively and quantitatively analyze the impact of different damage types on reservoirs. The results show that liquid phase invasion is the main damage mode, accounting for about 80%, while solid phase invasion is the secondary damage mode, accounting for about 20%. The penetration depth of solid phase is about 25-30 mm. Contrast experiments were designed and some measures such as adding micellar plugging agent HSM, inhibitor HAS and waterproof lock agent HAR-D were put forward to solve the problem of liquid phase invasion damage. It was found that the damage of filtrate decreased by 20%, the damage of water sensitivity decreased by 60%, and the damage of water lock decreased by more than 40%. The data prove that the proposed scheme can effectively reduce the damage of drilling fluid to ultra-low permeability reservoirs.