不同分支角度鱼骨井油水运动规律

Oil and Water Movement Patterns in Fishbone Wells with Different Branch Angles

相对于直井和水平井,鱼骨井具有单井控制储量高、油藏接触面积大等优势,但开发过程中往往需注水来即时补充地层能量。分支井井身结构复杂,现场常采用直井或水平井作为注水井构建不规则的注采井网,而实际生产过程中存在分支井含水上升快、产油量下降快和注水量调配难等问题,亟需开展不同注采方式和不同井型下的油水运动特征研究。利用二维可视化模型、红色染色煤油和黑墨水,通过物理模拟实验研究不同分支角度(30°~90°)鱼骨井一注一采井组在不同注采井型下的油水运动特征,并用数值模拟结果进行验证。结果表明,水平井注水时,油水前缘向分支处偏移更大,油水前缘的推进效果更为均匀;直井注水时,油水前缘推进较为缓慢,但水淹状态时的波及面积更大。直井注水时,分支角度为45°的鱼骨井采出程度(61.10%)最高;水平井注水时,分支角度为30°的鱼骨井采出程度(57.97%)最高,水淹状态时剩余油分布最少。当分支角度小于30°时,水平井的注水效果好;当分支角度大于45°时,直井的注水效果好。对比物理模拟实验和数值模拟实验的油水运动场图和采出程度,结果较为吻合,实验结果与适用油藏特征的匹配性较高。研究结果对实际的油田鱼骨井注采井网部署和参数优化等提供了一定的理论指导和参考依据。

Compared with vertical and horizontal wells,fishbone wells have advantages such as high single well control reserves and large reservoir contact area.However,in the development process,it is often necessary to inject water to supplement the formation energy in a timely manner.Branch wellbore structures are complex.Irregular injection-production well networks are often constructed using vertical or horizontal wells as injection wells on-site.However,problems such as rapid water rise in branch wells,rapid decline in oil production,and difficulty in allocating water injection rates exist during actual production processes.It is necessary to research on the characteristics of oil-water movement under different injection-production methods and different wellbore types.Using two-dimensional visualization models,red dyed kerosene,and black ink,physical simulation experiments were conducted to study the oil-water movement characteristics of fishbone well groups with different branch angles(30°—90°)under different injection-production well types,and then the numerical simulation results were validated.The results showed that when horizontal wells were injected with water,the greater offset of the oil-water front towards the branch resulted in a more uniform advancement of the oil-water front.When vertical wells were injected with water,the advancement of the oil-water front was slower,but the affected area in the water-flooded state was larger.When water was injected into vertical wells,the fishbone well with a branch angle of 45°had the highest recovery rate(61.10%).When water was injected into horizontal wells,the fishbone well with a branch angle of 30°had the highest recovery rate(57.97%),meanwhile,the distribution of remaining oil was the least in the water-flooded state.When the branch angle was less than 30°,the water injection effect of horizontal wells was better.When the branch angle was greater than 45°,the water injection effect of vertical wells was better.Comparing the oil-water movement field maps and recovery rates of physical simulation experiments and numerical simulation experiments,the results were quite consistent.The experimental results had a high matching degree with applicable reservoir characteristics.The research results provided theoretical guidance and reference basis for the deployment and parameter optimization of fishbone well injection-production networks in actual oilfields.