延长油田西部边底水油藏水平井优化设计及效果分析

Optimization Design for Horizontal Wells and Its Effect Analysis in Bottom Water Reservoirs of Yanchang Oilfield

延长油田利用水平井开发延安组底水油藏已显示出巨大潜力,但水平井参数设计尚未得到深入研究,其合理程度直接影响水平井的开发效果。以典型区块延安组油藏为例,在油藏地质特征研究的基础上,应用数值模拟技术,确定了不同油藏的水平井井网、水平井水平段方位、长度、垂向位置、井距等参数。结果显示,油藏规模较大时,优先采用错位半个井距、水平段垂直砂体方向的井网;油藏较小无法形成整体井网时,优先在油藏高部位沿构造平缓位置布井。水平井合理水平段长度为400m,合理位置应在距油层顶1/3以内位置,水平井合理井距为250m。用优化的参数对已实施的水平井进行了开发效果评价,结果显示,优化后延安组水平井日产油上升,递减变慢,综合含水较稳定,开发效果较好。参数设计对同类油藏水平井开发有一定的指导作用。

Horizontal well development shows great potential in bottom water reservoir of Yan＇ an Formation. However, in -depth research has not been conducted on parameters design of horizontal wells. Reasonable degree of the parameter de- sign directly affects the development effect of horizontal wells. Taking a reservoir of Yah＇ an Formation in a typical block as an example, we detellnined well pattern, length of horizontal section, vertical location of horizontal section, well spacing and other parameters of different reservoirs by employing the numerical simulation method based on the reservoir geology study of this block. Results showed that the well pattern with dislocation of half well spacing and perpendicular to the direc- tion of sand body at horizontal section was optimized when reservoir was large in scale. When the reservoir was so small that overall pattern could not be formed, the wells would be placed along gently-dipping structures at higher position of reser- voirs. Reasonable length of the horizontal section of horizontal wells was 400m, reasonable position should be at a distance of 1/3 within the reservoir top position, and horizontal spacing was 250m. In addition we evaluated the development effect of horizontal wells with optimized parameters. As a result, after parameter optimization, daily oil production of horizontal wells at Yan＇ an Formation rose, decline got slowly, comprehensive water cut was relatively stable, and development effect was better. It was revealed that parameter design had certain instruction function to horizontal well development in similar reservoirs.