沁水盆地南部煤层气问题井原因分析及技术探讨

Cause Analysis and Technical Discussion of CBM Problem Wells in Southern Qinshui Basin

随着沁水盆地南部煤层气的大规模开发,目前已完钻井和已进行煤储层改造的井中有多口井发生不同程度的套管损坏和固井质量等问题。针对不同问题提出了不同的处理思路,水泥浆返高在目的煤层顶界以上50m,采用挤水泥二次固井方式处理;水泥浆返高不足50m、目的煤层以下替空和水泥环胶结不连续,采用压裂新工艺进行储层改造;定向井中漏点在造斜点以上采用换套技术;漏点在直井封固段以上或定向井中封固段以上造斜点以下采用水泥封堵技术;漏点在封固段以下采用下4寸套管。

With the large-scale development of CBM in southern Qinshui Basin, the problems such as varying degrees of casing damage and cementing quality have appeared in many of the drilled wells and the coal reservoir reconstruction wells at present. Different processing ideas are proposed for different problems. If cement return height reaches up to 50m above the top boundary of the target coal seam, cement squeeze in the seeondary cementing is used. If cement return height is less than 50m and over-displacement of cement paste is below the target coal seam and discontinuous cementation of cement sheath, the new fracturing technology is applied to reservoir reconstruction. If the leakage point is above the isolation section in the vertical well or a- bove the isolation section and below the kickoff point in the deviated well, the cement plugging technology is applied. If the leakage point is blow the isolation section, 4 inch casing is used.