塔河油田碳酸盐岩储层恶性漏失空间堵漏凝胶技术

塔河油田10区某些碳酸盐岩储层段缝洞发育，且非均质性强、漏失空间大，常规桥堵技术很难实现有效封堵。聚合物凝胶易充填于漏失通道，通过自身交联强度以及与漏层壁面的黏结性实现有效封堵。以部分水解聚丙烯酰胺（HPAM）、六亚甲基四胺（HMTA）、对羟基苯甲酸甲酯（NIPAGIN）为核心处理剂，研制出了储层用抗高温堵漏凝胶。通过性能评价可知:该抗高温堵漏凝胶表观黏度在40~45 mPa·s范围内，140℃下成胶时间在4~10 h内可控；利用裂缝钢铁岩心（长5 cm）进行封堵能力评价，凝胶可有效封堵2~5 mm缝隙，封堵压力可达2.5 MPa，并在18 d内保持良好的封堵能力，22d后可实现自破胶返排；使用破胶剂可进一步提高破胶效率，在8 h内实现凝胶解除。该堵漏凝胶既可实现高效封堵，又能有效解堵，对储层段恶性漏失有着广泛的应用前景。 

Use Gel to Control Severe Mud Losses in Carbonate Reservoir Formations in Tahe Oilfield

Some carbonate reservoirs in Block 10 of the Tahe oilfield are developed with fractures and vugs, and are of high degree of inhomogeneity, resulting in severe mud losses difficult to bring under control with common bridging techniques. Polymeric gels, however, can be used because of their readiness to blocking the loss channels through their own crosslinking strength and sticking of the surfaces of the channels through which the mud is losing. Using partially hydrolyzed polyacrylamide (HPAM), hexamethylenetetramine (HMTA), methyl p-hydroxybenzoate (NIPAGIN) as the core additives, a high temperature gel used for lost circulation control in reservoirs was developed. Laboratory evaluation showed that the apparent viscosity of the gel is in a range of 40 – 45 mPa·s, and time for gelling under 140 ℃ is between 4 h and 10 h. Test of the gel on a fractured steel core (5 cm in length) showed that the gel was able to plug the fractures of 2–5 mm in width, and the pressures across the plugged fractures was 2.5 MPa, and was maintained within 18 d. The gel was broken and flowed back after 22 d of blocking. Efficiency of breaking the gel can be improved with gel breaker; the gel will get broken in 8 h when gel breaker is used. This gel, being able to both efficiently plug fractures and to effectively be removed, shows a broad prospect in controlling severe mud losses in reservoirs.