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大张坨储气库是我国的第 1个地下储气库 ,用于调整京津两地的用气量。在储气库区块上的库 8井是 1口定向井 ,固井有以下难点 :1.地层破裂压力低 ,易发生漏失 ;2 .地层压力系数低 ,产层易伤害 ;3.水泥封固段长 ,地温梯度高达 3.4℃ / 10 0 m,且使得上部水泥浆凝固时间长 ,影响水泥浆胶结质量。针对以上情况 ,采取了以下措施 :1.采用屏蔽暂堵技术 ,提高地层承压能力 ;2 .采用双级注水泥工艺 ,一级固井用常规水泥浆密度 ,二级固井采用低密度水泥浆 ,主要是漂珠和微硅共同配制的水泥浆体系 ;3.控制水泥浆失水量和自由水 ;4.增加套管扶正器用量 ,保证套管有较高的居中度 ,提高顶替效率。通过采取以上措施 ,经 SBT测井表明一级固井质量优质 ,二级固井质量合格。
Dazhang Tuo gas storage is China’s first underground gas storage, used to adjust the amount of gas used in Beijing and Tianjin. The well 8 in the reservoir block is a directional well. The cementing has the following difficulties: 1. The fracturing pressure in the formation is low and the leakage is easy to occur. 2. The formation pressure coefficient is low and the production layer is easy to be damaged. 3. The cement seal Solid length, geothermal gradient as high as 3.4 ℃ / 10 0 m, and makes the upper part of the solidification of cement slurry for a long time, affecting the cementing quality of cement. In view of the above situation, the following measures have been taken: 1. Adopt the temporary shield blocking technology to improve the bearing capacity of strata; 2. Adopting two-stage injection cementing technology, the conventional cement slurry density for the first cementing and the second cementing are low- Pulp, mainly floating beads and micro-silicon jointly formulated slurry system; 3. To control the loss of water and free water slurry; 4. Increase the amount of casing centralizer to ensure that the casing has a higher degree of centering to improve the replacement efficiency. By taking the above measures, SBT logging shows that the quality of primary cementing is good and the quality of secondary cementing is qualified.