大张坨地下储气库注采井固井实践

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℃/100 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。

CEMENTING OF THE INJECTION AND PRODUCTION WELLS OF UNDERGROUND GAS STORAGE IN DAZHANGTUO

Dazhangtuo gas storage is used to adjust the gas supply in Beijing and Tianjin. Well Ku8 is a directional well drilled in the gas storage block, and its cementing is difficult due to the following problems:1. Low formation fracture pressure, which can cause lost circulation; 2. Low formation pressure factor, which can lead to formation damage; 3. Long cementing interval, and high thermal gradient of 3.4℃/100m, which delays the setting time of upper cement slurry and impacts its gelling. The following measures are adopted to cope with these problems:1. Adopt the temporary shielding cementing technique, to improve the pressure bearing ability of the formation; 2. Apply two-stage cementing. Common cement slurry is used for the first stage cementing, and lightweight cement mainly composed of micro sphere and micro silicate are used for second stage cementing; 3. Control the fluid loss of the cement and the content of free water; 4. Use more casing centralizers to improve the displacement efficiency. SBT logging shows a good cementing job in this well.