A Kind Of Work Can Cure Plugging Fluid System Research

The northeastern of Sichuan is one of the best carbonate reservoir physical property regions that has verified in our country at present. It is rich in natural gas resources. But because of the complex geological structure, broken strata and vegetal split and pore, the same open hole section is different in the aspect of pressure coefficient, which makes frequent and serious lost circulation and plugging job very difficulty. In view of the problem that the northeast of Sichuan encountered lost circulation easily in the process of drilling, in the basis of summing-up the traditional lost circulation materials and its technology, and depending on the guiding ideology of chemistry working liquid, this paper developed a new type of working liquid which can solidify and plug.According to the engineering performance requirements of working liquid, this paper chooses GYW-301and sodium bentonite as suspension stabilizer for making up basic liquid of plugging liquid, meanwhile sodium bentonite also has the ability of controlling fluid loss performance of plugging liquid. This paper chooses slag as curing agent, which can realize solidification through the activator, and finally determined the JH-A and JH-B as activator, and optimized GYW-601as the early strength agent, GYW-401as fluid loss additive, GYW-701as retarder and WTD-300as inert lost circulation material.Indoor experiment results show that in the basis of suspension stabilizer GYW-301, the addition of suitable amount of sodium bentonite can make plugging liquid have good suspension stability, in the common function of the activators JH-A and JH-B and early strength agent, solidification and plugging liquid has good compressive strength, in the common function of fluid loss GYW-401and bentonite the fluid loss of solidification and plugging liquid can be controlled within100ml, the retarder GYW-701can effectively regulate the thickening time and has no effect in the compressive strength. Through regulating the comprehensive performance of different density the plugging liquid, the results show that: solidification and plugging liquid is adjustable in the density range of1.30～2.35g/cm3, with good ability of the suspension, flow capacity, strong thixotropism performance and solidification performance, in the50℃-70℃temperature, the24hours compressive strength can be above10MPa. In30℃～145℃temperature, solidification and plugging liquid has the good stability and thickening time can effectively regulate, which can meet different well depth to the requirements of the temperature.At the same time the plugging liquid and drilling fluid has good compatibility, and can solidified when they are mixed, which ensured the safety of the construction. Plugging simulator evaluation results show that the plugging liquid has strong sealing characteristics when compounding with lost circulation material WTD-300, which can improve the formation pressure7MPa, and the plugging liquid be experimented in two well fields in the northeast of Sichuan, the experiment showed that the new type of solidification and plugging liquid successfully plugged fractured formation, and greatly improved the bearing pressure ability of leakage, the successful application of the solidification and plugging liquid has very good development prospect for alleviating fractured lost circulation problems in the northeastern area of Sichuan.