_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 230249, “First In-Situ Combustion Test in the Permian Basin, ” by Hao Ye, Leila Karabayanova, SPE, and Eduardo Orozco, SPE, Texas A&M University, et al. The paper has not been peer-reviewed. _ Hydraulic fracturing in the Permian Basin typically recovers only 8–12% of the original oil in place, leaving large volumes of hydrocarbons untapped. This study investigates in-situ combustion (ISC) as an alternative enhanced oil recovery (EOR) method, with particular emphasis on the role of rock and brine in enabling combustion sustainability in light-oil systems. Unlike refracturing, ISC establishes a self-sustained thermal drive that can mobilize bypassed oil and alter reservoir properties. Introduction ISC is a thermal EOR method where air or oxygen-enriched gas is injected into a reservoir to ignite a portion of the oil in place. The combustion generates heat that reduces oil viscosity, mobilizes trapped hydrocarbons, and creates flue gases that help drive oil toward producing wells. The main principle is to sustain a stable combustion front that advances through the formation while simultaneously benefiting from enhanced mobility of the displaced oil. This process improves sweep efficiency and maximizes recovery beyond that which conventional methods or waterflooding can achieve. Experimental work on ISC in Permian shales is limited and centers on a few Wolfcamp studies using a small-batch kinetics reactor, a closed accelerating rate calorimeter with crude-oil fractionation, and thermal-kinetics simulation. To date, no standard combustion-tube experiments have been conducted on Permian Basin outcrops to assess coupled oil/water/rock interactions and the ability to sustain front propagation. Moreover, unlike other EOR methods, ISC has not been applied at the field scale in the Permian Basin. Despite numerous ISC studies on kerogen-rich shales, most of them rely on small-scale core plugs or crushed-rock microreactors, which are useful for defining ignition thresholds and intrinsic kinetics, but are limited for assessing the sustainability and stability of combustion-front propagation in shale plays. This work addresses that gap by presenting the first combustion-tube experimental study, using native Midland crushed core samples, reservoir crude oil, and formation brine. Real-time, in-situ measurements of ignition conditions, peak temperature, combustion-front velocity, and produced-gas composition were integrated with pre- and post-test rock and fluid analyses including scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), total dissolved solids (TDS), pH, and oil-viscosity measurements to quantify in-situ combustion behavior and efficiency. Materials and Methods To simulate reservoir conditions of the Midland Basin, crushed rock samples were saturated based on pore volume capacity with 50% crude oil and 50% formation brine, then packed into a stainless-steel combustion tube (length 102 cm, diameter 7. 3 cm). A central thermowell equipped with 16 thermocouples at 5. 1-cm intervals monitored the combustion-front movement. Ignition was initiated by an external band heater applied to the top 10 cm of the tube, with 350°C established as the minimum ignition temperature for Permian crude oil. To reduce heat losses, the tube was wrapped with fiberglass-cotton insulation and an outer calcium silicate jacket.
Chris Carpenter (Mon,) studied this question.