重力泄水辅助蒸汽驱采油工艺技术研究与试验

洼59块为深层中厚层状特超稠油油藏。区块已进入高轮次吞吐阶段,吞吐效果逐轮变差,采油速度急剧递减。采用重力泄水辅助蒸汽驱技术,探索深层特超稠油油藏蒸汽吞吐开发后期开发方式的转换。该技术采用直井、水平井组合开发模式,上叠置水平井注汽,下叠置水平井辅助排液,周围直井产油。针对工艺技术难点,通过汽水分离器、高效隔热管柱和环空注氮隔热的综合应用,实现了深层稠油油藏井底干度大于45%的目标;采用双管注汽技术使水平段得到高效动用;通过电加热降黏和防偏磨技术的成功应用,解决了试验初期黏度大、水平井杆管偏磨的问题;利用越层深抽和高温大排量举升解决了提液降压、深层高温大排量举升的难题。井组整体效果明显,产液量由179t/d增大到最高值526.9t/d,产油量由31.0t/d增大到最高值96.5t/d,含水由91.1%下降到平均值84.69%。

Research and Pilot Project of Oil Production Technology of the Gravity Water Drainage Assisted Steam Flooding

Block Wa59 is the deep medium-bedded extra super heavy oil reservoir.It has entered into high cy- cle huff and puff stage,the effect is becoming worse gradually and oil production rate has been declined sharply.Technology of gravity water drainage assisted steam flooding is applied to the transform of the steam stimulation development method at the later stage in the deep extra super heavy oil reservoir.Development mode of it is the combination of vertical wells and horizontal wells ,and steam will be injected in the upper horizontal wells and water will be drained for assist in the bottom horizontal wells and the vertical wells around produce oil.We have achieved the goal of more than 45% of the bottom steam dryness in the deep heavy oil reservoir through the integrated application of steam-water separator,efficient insulated tubing string and annulus nitrogen injection according to the analysis of technology diffficuhy.The horizontal sections have been produced efficiently by the use of two-pipe steam injection technology.We have solved the problems of high early testing viscosity and eccentric wear of horizontal rod in the horizontal well through the viscosity drop by electric heating and the successful application of the prevention technology of eccentric wear.The dif- ficulties of pressure drop through liquid production raise and large displacement lifting at deep layers with high temperature have been solved using the deep lifting cross strata and large displacement lifting at high temperature.The effect of whole well group is obvious,liquid production capacity has increased to maximum value 526.9t/d from 179t/d,oil production has increased to maximum value 96.5t/d from 31.0t/d,and water cut has dropped to average value 84.69% from 91.1%.