全过程欠平衡随钻测试替代钻柱测试探讨

DST Replaced by TWD in Underbalanced Drilling

通常利用测试手段获得地层压力、流量、温度、渗透率、流体类型、地层污染程度等信息。当用欠平衡方式打开储层时,地层流体通过渗流进入井筒,地面的油气监测数据,能及时反映储层信息。地层流体返到地面,由地面的四相分离器进行分离、计量、点火或回收。地层压力通过随钻测压系统、关井求压或者循环测试的方法得到,通过节流阀开启和关闭实现开关井作业,通过记录地面套压、立压随时间变化反算井底压力变化或者通过钻柱压力计记录压力,以便得到同测试一样的压力恢复曲线,地层流体样品通过钻杆井下取样枪取得。用全过程欠平衡随钻测试替代钻柱测试,不仅节约了测试和压裂费用,对于没有商业价值的井来说,还节省了完井费用,同时压力监测数据和流量监测数据可以反映钻井过程中出现的一些井下复杂情况,为相应的技术决策提供依据,提高了钻井的综合经济效益。

Generally the data of porous pressure,flow rate,temperature,permeability,fluid type and the level of formation damage etc were obtained through tests.When the reservoir was opened by under-balanced drilling,the formation fluids entered into wellbore by filtration,the reservoir information could be reflected by surface detecting data.The formation fluids would be separated,measured,fired and recycled by four-phase separator on the surface.The formation pressure could be obtained through FPWD system,calculating pressure by shut-in,UBD circulation,wells were Opened or closed through throttle value,to record surface casing pressure,standpipe pressure changing with times,or record bottom hole pressure through drill string to get pressure distribution curve similar with that of test.The sample of formation fluids can be gained by means of sampling gun placed in drill string.TWUBO replacing test not only can save the cost of test and fracturing,but the expense of completion can also be saved for those wells without commercial significance,at the same time,complex downhole condition can be reflected by the downhole pressure and flow monitoring data for providing corresponding basis for technical decisions,therefore the integral economical benefit can be boosted.