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Imbibition Oil Recovery From Tight Rocks With Dual-Wettability Networks in the Montney

Fig. 1—Recovered oil (yellow droplets lined up at the surface of the sample) is observed along the depositional laminations of an oil-saturated sample immersed in brine.

Previous studies demonstrate that Montney rock samples present a dual-wettability pore network. Recovery of the oil retained in the small hydrophobic pores is uniquely challenging. In this study, the authors applied dual-core-imbibition (DCI) methods on several Montney core plugs and introduced the imbibition-recovery (IR) trio to investigate the recovery mechanisms in rocks with dual-wettability pore networks.

Introduction

Spontaneous imbibition of aqueous phases (water, brine, or surfactant solutions) in fractured sandstone has been studied as a possible mechanism for enhanced oil recovery. Extensive experimental and mathematical investigations have been conducted for relating the imbibition rate and total oil recovery to the capillary and gravity forces and geometrical parameters. However, rock/fluid interactions in tight and shale reservoirs are more complicated than those seen in conventional reservoirs. In addition to capillary forces, organic materials and reactive clay minerals can influence the fluid flow and storage in the small pores of low-permeability rocks. The affinity of reservoir rock to a particular fluid in such formations depends especially on rock mineralogy and properties of the organic matter that coats and fills the pores.

Previous comparative imbibition tests show that the affinity of the Montney samples to oil is significantly higher than their affinity to water. This behavior was explained by the presence of water-­repellent pores within or coated by solid bitumen or pyrobitumen. In the complete paper, the authors focus on imbibition oil recovery of samples cored from the Montney Formation and investigate the role of rock-fabric complexities, such as dual-wettability characteristics, in oil recovery by water imbibition. A detailed discussion of materials used in the spontaneous-imbibition and oil-recovery tests, including rock and fluid properties, is included in the complete paper.

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 185076, “Imbibition Oil Recovery From Tight Rocks With Dual-Wettability Pore Networks: A Montney Case Study,” by Ali Javaheri and Hassan Dehghanpour, SPE, University of Alberta, and James Wood, SPE, Encana, prepared for the 2017 SPE Canada Unconventional Resources Conference, Calgary, 15–16 February. The paper has not been peer reviewed.
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Imbibition Oil Recovery From Tight Rocks With Dual-Wettability Networks in the Montney

01 October 2017

Volume: 69 | Issue: 10

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