一种提高致密油藏低产水平井产量的重复改造方法

A REFRACTURING APPROACH TO ENHANCE PRODUCTIVITY OF LOW-PRODUCTION HORIZONTAL WELLS IN TIGHT OIL RESERVOIR

近年来,以华庆长×为代表的鄂尔多斯盆地致密油藏采用水平井分段压裂技术开发,单井产量得到了大幅提高,达到周围直井的3~5倍。但是受到初次改造规模小的影响,出现了部分水平井低产低效的问题。通过评价不同低产原因水平井的增产潜力,确定了体积压裂的重复改造思路。另外,结合水平井老井固井质量、套管完善程度、施工管柱等因素,研究并形成了"组合油管+大通径封隔器+大通径喷砂器"三封单卡压裂工艺,配合低摩阻压裂液,排量可达5 m^3/min以上,具备了储层形成复杂裂缝的条件。现场试验2口井,措施后日增油量达到4~6 t。井底压力监测表明净压力达到了克服水平两向应力差的条件,表明该技术对水平井老井重复改造具有较好的适应性,对其他致密储层水平井重复改造具有借鉴意义。

In recent years,stage frac was used to develop the tight oil in Ordos Basin,the oil production was enhanced as3 to 5 times the vertical well' s production in the same area.However,partial horizontal wells exhibited low production low efficiency because of the inadequate primary stimulation.By evaluating the production-enhancing potential of the poor production horizontal wells,refracturing was put forward.And taking into consideration the cementing quality of old horizontal wells,the casing integrity,the working string,etc.,a frac process with composite tubing string,large-bore packer and large-bore sand blasting device was determined,the low friction frac fluid could be pumped up to 5 m /min each stage,able to creating complex fractures in reservoir formation.This technology was tested in 2 wells,the oil production was increased by 4 to 6 tons per day.The BHP monitoring showed that the net pressure was high enough to counter the horizontal stresses in 2 directions,proving this technology would be applicable for secondary stimulation in old horizontal wells.It will be a reference for other tight oil reservoirs.