Abstract:

Because of friction loss in horizontal wellbore, pressure drop of horizontal wellbore may equal to that of reservoir pressure drop, which results that the reservoir pressure drop at the tip of horizontal wellbore is rather small or equals to zero, this phenomenon often appears in high permeability or coning reservoirs, pressure difference of these reservoirs is low or limited.Therefore, studying the design method of optimal horizontal wellbore length has a guide meaning to development program design of horizontal wells.By dividing three reservoir type cases (bottom water drive reservoir, gas cap and bottom water drive reservoir, gas cap drive reservoir), the paper derives flow model in reservoir, flow model in horizontal wellbore, the optimal length model of horizontal wellbore, in the process of derivation, the factors, such as flow regime (laminar flow, turbulent flow) and relative roughness of wellbore, which have influence on productivity of horizontal wells, are considered.Finally, the paper gets a few conclusions by example calculation.

Key words: horizontal wells, optimal length, laminar flow, turbulent flow, friction loss, design, method

摘要：

由于水平井水平段内摩擦损失的缘故,如果水平段内压降和油藏压降相当,导致水平段末端压降很小或者为零,这种现象常常出现在高渗透层的低压降生产油藏和生产压差受到限制的锥进油藏。因而研究水平井最优长度设计方法对水平井开发方案设计具有指导意义。本文分三种情况(底水油藏、气顶底水油藏、气顶油藏)建立了油藏内流动模型、井筒内流动模型、水平井水平段最优长度数学模型,在建立模型过程中,考虑了水平段内流动状态(层流、紊流)和管壁相对粗糙度对摩擦损失和水平井产能的影响,最后通过实例计算得到了几个结论。

关键词: 水平井, 最优长度, 层流, 紊流, 摩擦损失, 设计, 方法