拉氏域中水平井压力动态计算新方法

Advances in Geo-Energy Research, 2018, 2(4): 393-403

原文网址: http://www.astp-agr.com/index.php/Index/Index/detail?id=81 

  当水平井筒流体流速过高或井筒内壁粗糙度较大时，水平井筒中的流动阻力较大，压力损耗不容忽视。传统的考虑水平井筒内压力降落的不稳态压力或产能的计算方法主要有两大类，其一是直接在井筒理想流动模型中加入压力降落系数，但该方法无法考虑流量沿井筒的不均匀分布，计算结果误差较大；其二是考虑流量沿井筒的不均匀分布，在实时域中计算井底压力或产能，但该方法计算速度较慢，且无法考虑井筒储集效应及表皮因子的影响。

本文通过定义新的水平井筒等效渗透率和等效导流能力，且将水平井等效导流能力考虑为沿井筒不均匀分布的函数，并通过积分变换将变导流问题转化为常导流问题，最终将考虑井筒压力降落的水平井压力动态计算模型转化为与有限导流垂直裂缝井模型形式相同的方程。计算所得结果与前人结果吻合较好，计算速度相比前人方法显著提高。分析表明，当水平井穿透比高时，模型所得结果与垂直裂缝井较为接近。此外，通过拟压力和拟时间函数变换，本文模型也可拓展至水平气井当中。

A new algorithm for computation of horizontal-well pressure in Laplace domain

Mingtao Wu, Wanjing Luo, Xiaodong Wang

(Published: 2018-08-18)

CorrespondingAuthor and Email: Wanjing Luo, luowanjing@cugb.edu.cn

Citation: Wu, M., Luo, W., Wang, X. A new algorithm for computation of horizontal-well pressure in Laplace domain. Advances in Geo-Energy Research, 2018, 2(4): 393-403, doi: 10.26804/ager.2018.04.04.

ArticleType: Original article

Abstract：

    The effect of wellbore pressure drop on horizontal well pressure response is relatively important when flow velocity is high or the surface of horizontal wellbore is rough. The objective of this study is to develop a stable and robust algorithm in Laplace domain to analyze horizontal-well pressure with pressure drop along the wellbore. Based on the novel definitions of horizontal well permeability and conductivity, the equation of fluid flow along a horizontal wellbore with pressure drop has the same form as that of fluid flow in a varying-conductivity fracture. A new dimension transformation has been used to change the varying-conductivity model into a constant-conductivity model, and then an iterative procedure has been introduced to obtain the pressure. This algorithm is developed in Laplace domain and eliminates the need for computations in the time domain. Besides, the skin effect and wellbore storage is easily to be taken into consideration.

Keywords: Computation algorithm, horizontal well with pressure drop, varying conductivity, Laplace domain.

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