分支参数对天然气水合物羽状多分支井降压开采产能的影响规律

天然气水合物是未来极具发展潜力的清洁能源,而多分支井开采技术是天然气水合物高效开采的一种值得进一步探索的技术方法。基于南海神狐海域SHSC-4试采井测井曲线数据,建立了理想水合物藏分层地质模型。分析了羽状多分支井布设在水合物Ⅱ层中部时,分支参数对降压开采产能的影响规律。结果表明:(1)分支参数优化时,应首先考虑分支长度;尤其是当分支长度较短时,分支长度增加的增产效果最强;随着分支长度增加到一定长度,继续增加分支长度的产能增幅逐渐减弱。(2)其次应考虑分支数目和分支角度;相较于增加分支长度,增加分支数目和分支角度对产能影响较弱且增产效果相近;基于钻井成本考虑,分支数目不宜过多;分支角度大于45°时,产能增幅呈下降趋势,因此分支角度应小于45°。(3)在充分考虑上述分支参数的基础上,可适当考虑分支间距。相较于其他分支参数,增加分支间距对产能影响最弱,在保证较大控制面积和充分考虑钻井成本的前提下,分支井间距越大越好。

Influences of branch parameters on depressurized productivity ofnature gas hydrate pinnate multilateral well

Natural gas hydrate is a clean energy with great development potential in the future, and the multilateral well technology is a technical method worthy of further exploration for the efficient exploitation of natural gas hydrate.Based on the logging curve data of the SHSC-4 test well in the Shenhu area of the South China Sea, a ideal hydrate reservoir stratified geological model was established. The influence of branch parameters on depressurization production capacity is analyzed when pinnate multilateral wells are located in the middle of hydrate layer II.The results show that: (1) When optimizing branch parameters, the branch length should be considered first; especially when the branch length is short, the increasing effect of branch length is the strongest; as the branch length increases to a certain length, the productivity increase gradually decreases with the increase of branch length.(2) Secondly, the number and angle of branches should be considered; compared with increasing the length of branches, increasing the number and angle of branches has a weak impact on productivity and has similar effect; based on the consideration of drilling cost, the number of branches should not be too much; when the branch angle is greater than 45 degrees, the productivity growth tends to decline, so the branch angle should be less than 45 degrees.(3) On the basis of fully considering the above branch parameters, the branch spacing can be properly considered. Compared with other branch parameters, increasing branch spacing has the weakest impact on productivity. On the premise of ensuring large control area and fully considering drilling cost, the larger the branch well spacing is, the better.