提高直井与水平井组合SAGD泄油速率技术研究

Technologies for Raising the Oil Drainage Rate with Vertical-Horizontal Well Combinations in SAGD Mode

  • 摘要: 针对辽河油田直井与水平井组合SAGD井组在开发过程中存在泄油速率低、蒸汽腔扩展不均匀等问题,以R.M.Bulter建立的双水平井泄油模型为理论基础,将直井与水平井简化为双水平井,在考虑端点效应有限长度水平井日产量方程的基础上,建立了水平井的泄油速率模型,并得到直井与注汽水平井组合SAGD上产和稳产阶段的泄油速率方程。分析泄油速率方程发现,直井与水平井组合SAGD井组泄油速率的主控因素为泄油井点数和蒸汽腔纵向扩展高度,结合辽河油田稠油开发实践,给出了直井与水平井组合SAGD井组提高泄油速率的技术措施,即水平段跟部注汽井增加2口,并将注汽井注汽排量提高20%,同时将最佳射孔位置设在靠近低物性段处,补孔长度确定为8 m。该技术在辽河油田6井组进行了现场应用,日产油量均呈现不同程度的上升,取得阶段性成功,为进一步提高SAGD井组泄油速率奠定了良好的基础。

     

    Abstract: Due to the low drainage rate and the uneven expansion of steam cavity appearing in the development of the Liaohe Oilfield which utilizes a vertical-horizontal well combination by steam assisted gravity drainage (SAGD), a horizontal-well drainage rate model was developed. It focused on a daily output equation for horizontal wells which have limited length and take into account the point effect (following the theory of R. M. Butler). With a dual-horizontal-well drainage model, and the vertical-horizontal well group was simplified as dual horizontal wells, finally, the drainage rate equation that was used for vertical well and horizontal steam injection well in SAGD. The drainage model was developed and applied to the stages of initial production and stable production. It is shown from the analysis on drainage rate equation that the drainage rate of vertical-horizontal well group SAGD is mainly controlled by the quantity of oil drainage wells and the vertical expansion height of the steam cavity. Combined with the heavy oil development practice in Liaohe Oilfield, the technical measures for increasing the drainage rate of vertical-horizontal well group SAGD were proposed. The approach involved drilling another two steam injection wells at the heel of the horizontal section and to increase the steam injection rate by 20%. Meanwhile, the best perforation position was set near the sections with low physical properties, with reperforation length of 8 m. These technical measures were applied to 6 well groups in the Liaohe Oilfield, and as a result, the daily oil production increased by different percentages. This research with field test provides the good basis for further improving the drainage rate of SAGD well groups.

     

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