涩北气田防砂工艺技术的研究与应用

A Technology of Sand Control and Its Application to Sebei Gasfield

柴达木盆地涩北气田属于第四系疏松砂岩气藏,其储层胶结疏松、易出砂。随着气田开发的深入,产层出砂严重,出水加剧出砂等,影响了气井的正常生产及气田的高效开发。通过多年的探索研究,进一步明确了涩北气田的出砂机理,形成了适合涩北气田的割缝管压裂充填防砂工艺技术。该工艺施工简单,一趟管柱可完成下防砂工具、充填、丢手多个工序。防砂后可形成防砂割缝管、砾石层等多级挡砂屏障,能有效阻挡地层出砂;同时,可对物性差产层进行改造,提高产层的导流能力。截至2015年底,共开展割缝管压裂充填防砂井47口,有效率83.0%,最长有效期5年以上,总体投入产出比1∶7.5。

In Qaidam Basin, Sebei gasfield belongs to the Quaternary unconsolidated sandstone gas reservoirs, which are composed of cementing and loose rocks easily bringing about sand production.Along with a further development, there are some problems affecting not only a normal production of gas wells but also an efficient development of gas field, containing plenty of sand production, and much water yield even increasing sand production. After long research on Sebei gasfield, the sand-producing mechanisms were made clear and a technology of frac-packing sand control by slotted liner formed. This technology is characterized by simple installation, and a one-trip string is able to implement three procedures of landing sand-control tools, packing, and releasing; moreover, multiple-stage sand barriers of both sand control slotted liner and gravels may effectively stop sand producing from layers; in addition, it may reform those pay zones with poor petrophysical property and increase their flowing capacity. By the end of 2015, there were 47 gas wells implementing frac-packing sand control by slotted liner,and the efficiency reached 83.0 % and the longest effective time was more than 5 a. Generally, the input-output ratio achieves 1:7.5.