防止低渗透储层污染的抽汲排液管柱的设计与应用

低渗透储层经过一段时间排液后,地层能量下降,完成抽汲排液后在解封、起排液管柱 过程中,势必使大量环空水倒灌进地层,对地层产生二次污染,影响地质资料的准确性、可信性。针 对这种情况,设计了两种抽汲排液管柱,在排液结束时砸断反循环阀销子,抽出井筒内环空水;若发 生砂卡,可采用正洗井冲净上封隔器上部沉积的砂子,既可解除砂卡,又避免大量洗井地面水进入 地层,大大降低对压后排液层的再次污染,确保合排后不再对地层产生二次污染及合排后求单层地 质资料的准确性。经过现场实际应用,效果显著。

Design and Application of Swabbing Out- Flow String for Preventing Pollution Against Low Permeable Reservoir

After a period of out flow for low permeable reservoir, formation energy decreases that makes lots of annulus water pouring into formation inversely during the time of upsetting packer and hoisting up string when the operation of swabbing outflow being finished which causes the second pollution to reservoir influencing accuracy and liability of tested geology data. For this situation, two kinds of swabbing out-flow strings are designed that are to swab annulus water by breaking off inverse sub pin after out flow or to wash up accumulating sand over the packer if stuck by sand that not only releasing sanding stuck, but also avoiding quantity of water pouring into formation which decreases a second time pollution to postfrac out-flowing layer greatly and makes sure the second pollution no longer happening and accuracy of geology data for single layer after combination of out-flow. By field applications, the results are obvious.