Review: Horizontal, directionally drilled and radial collector wells

Georg J Houben,Thomas Daffner,Falk Triller,Mark Bakker,Anvar Kacimov,Sarah Collins

doi:10.1007/s10040-021-02425-w

Abstract

Horizontal wells play an often overlooked role in hydrogeology and aquifer remediation but can be an interesting option for many applications. This study reviews the constructional and hydraulic aspects that distinguish them from vertical wells. Flow patterns towards them are much more complicated than those for vertical wells, which makes their mathematical treatment more demanding. However, at some distance, the drawdown fields of both well types become practically identical, allowing simplified models to be used. Due to lower drawdowns, the yield of a horizontal well is usually higher than that of a vertical well, especially in thin aquifers of lower permeability, where they can replace several of the latter. The lower drawdown, which results in lower energy demand and slower ageing, and the centralized construction of horizontal wells can lead to lower operational costs, which can make them an economically feasible option.

Highlights

Horizontal wells (HW), including radial collector wells (RCW) and horizontal directionally drilled wells (HDDW) are, from a hydraulic and economical point of view, an interesting alternative to vertical wells for a variety of hydrogeological situations
This study aims at closing this gap by addressing: the evolution of HWs and their fields
Horizontal captures are one of the oldest techniques employed for groundwater recovery. They have been mostly replaced by vertical wells

Summary

Introduction

Horizontal wells (HW), including radial collector wells (RCW) and horizontal directionally drilled wells (HDDW) are, from a hydraulic and economical point of view, an interesting alternative to vertical wells for a variety of hydrogeological situations. Their potential is, often overlooked, due to the scarcity of practical examples, qualified companies and specialized planners. Many of them from the oil and gas industry, discuss the hydraulics of such wells, there is a lack of a comprehensive description of all aspects of HWs from the groundwater perspective. The focus here will be single-phase groundwater flow, many technical developments and mathematical models for horizontal wells come from the oil and gas industry, where the operators are interested in both single-phase (crude oil) and multiphase flow (secondary and tertiary stages of hydrocarbons recovery) from porous/fractured formations. The review incorporates a wealth of older literature, which is often overlooked as they are only available in German, French, Russian or Polish (Falcke 1962; Nöring 1953; Polubarinova-Kochina 1955, 1977; Stack 1958; Borisov et al 1964; Schneebeli 1966; Grigoryan 1969; Wiederhold 1966a, 1966b; Kotowski 1985, 1988; Iktisanov 2007; Khisamov et al 2017)

Objectives

Methods

Findings

Conclusion