盐穴地下储气库对流井老腔改造工艺技术

A technology of reconstructing salt cavern underground gas storages by use of the old chambers of those existing convection wells

国内盐矿存在的老腔主要为对流井老腔,但目前国内外暂无对流井老腔改建为盐穴地下储气库的案例。为了充分增加盐腔的有效体积,在对比不同改造技术的基础上,提出封堵原有两口老井并钻新井,在通道中间打一口排卤井与原水平通道对接的对流井老腔改造工艺技术,并采用该工艺技术对国内某对流井老腔进行了改造试验。研究结果表明:①在水平通道中间打一口连接井的技术切实可行,可最大限度地利用盐腔下部残渣中的孔隙体积,并且改造后的盐腔能够满足储气库注采运行的要求;②在不溶物残渣中卤水排出20%~40%的情况下,试验井可增加腔体体积13.94×10^4~27.88×10^4m^3,增加工作气量1763×10^4~3526×10^4m^3。结论认为,该对流井老腔改造技术可充分排出对流井老腔不溶物残渣中的卤水,大幅度提高盐穴腔体的有效体积,可推广到类似对流井盐腔的改造实践中,具有广阔的应用前景。

The existing caverns in salt mines in China are mainly convection wells. However, there is no case of using those existing convection wells to reconstruct UGS at home and abroad at present. In order to fully increase the effective volume of such salt chambers, we put forward the technology of plugging two old wells and drilling new wells, then drilling a brine drainage well in the middle of the channel to connect with the original horizontal channel, based upon a comparison analysis with other reconstruction technologies. Taking a convection well as an example, the test results show that the technology of drilling a connecting well in the middle of the horizontal passage is feasible, and the pore volume in the lower residue of the salt chamber can be mostly utilized. The reformed chamber can also meet the injection–production operation requirement of a UGS. If 20–40% brine in the insoluble residue can be discharged , the chamber volume can be increased by 139.4–278.8 thousand m3 and the working gas can be increased by 17 630–35 260 thousand m3. In conclusion, this technology can fully discharge the brine from the insoluble residue and increase the effective volume of the salt chamber. It shall be popularized and applied to similar convection wells, and has broad application prospects.