Evaluation of flow leakage through abandoned wells and boreholes

Abstract

Flow leakage through abandoned wells and improperly plugged boreholes drilled between hydrogeologically separated water‐bearing zones represent potential pathways of contamination. The present study provides an analytical evaluation of the transient flow rate through these artificial conduits and the resulting hydraulic head distributions when (1) artificial gradients are created by an injection well operating in one of the aquifers or (2) natural hydraulic head differences are present between two confined aquifers. The analysis is conducted by solving the groundwater flow equations in the confined aquifers that are coupled by the flow through the well or borehole. A case study was investigated involving contamination leakage through abandoned wells and improperly plugged boreholes caused by the operation of deep waste injection wells.

A harmonic pulse testing method for leakage detection in deep subsurface storage formations

“…For the leak scenario, a leaky well is present at a distance r I from the injector, and the distance between the leaky well and observation well is denoted by r L . Such a problem setting has been widely used in analytical and numerical studies for leakage modeling [e.g., Avci, 1994;Birkholzer et al, 2011;Cihan et al, 2011;Nordbotten et al, 2004;Sun and Nicot, 2012;Sun et al, 2013b;Zeidouni, 2014]. Most of the previous analytical studies assume constant injection rates.…”

“…The first method uses a published solution in time domain [Avci, 1994], the second method compares the analytical solutions to discrete HðxÞ values obtained using inverse Laplace transform and FFT, and the third method uses a finite element model. Parameters used for this benchmark problem are listed in Table 1.…”

“…A primary environmental concern of these practices is the potential migration of injected fluids through connected pathways (e.g., abandoned wells or geologic faults) into underground sources of drinking water. A number of previous works have focused on forward and inverse modeling of leakage from deep subsurface storage formations [e.g., Avci, 1994;Cihan et al, 2011;Javandel et al, 1988;Nordbotten et al, 2004;Sun and Nicot, 2012]. Most of these analyses assume passive monitoring, in which pressure gauges are simply used to ''listen'' for possible leak signals.…”

An iterative global pressure solution for the semi-analytical simulation of geological carbon sequestration

“…This algorithm creates a set of linear equations describing the pressure distribution throughout the domain by superimposing pressure changes caused by each source or sink in each aquifer. The general algorithm presented in [38] in conjunction with the development of a multiphase pressure response function [33,34,35,38] has led to a semi-analytical CO 2 leakage algorithm, presented in [40] and expounded upon in [7] and [36], which estimates both brine and CO 2 flux across confining layers resulting from the injection of CO 2 . While there are multiple pathways for the leakage of sequestered CO 2 from subsurface storage reservoirs (e.g.…”

“…geological discontinuities, caprock permeability, etc. ), [40] assumes that hydrocarbon exploration and production boreholes created preferential flow paths in the domain [2,3,12,14,18,28,32]. This assumption appears reasonable as the existing caprock had successfully held the recently produced hydrocarbons for many millennia prior to production [37].…”