Experimental and Statistical Investigation of In-House Surfactant Formulations and Their Imbibition Capacity for Selected Core Substrates

Abstract

Spontaneous imbibition in porous media is a pervasive part of many natural and industrial processes. It is an inherent feature of fluid transport in porous media and is a key driver in oil recovery. Understanding spontaneous imbibition and leveraging surface science is fundamental for fluid recovery. Specifically, the role of the surfactant structure-function relationship in imbibition processes and its potential to alter the capillarity and wettability of the reservoir rock is advantageous for improved oil and fluids mobility and recovery. The success of the surfactant relies on understanding the factors governing the interfacial phenomena among the crude oil, brine, and formation properties under reservoir conditions. Developing a methodology coupling chemical performance with analytical techniques, and statistical interpretation of core–surfactant–oil interactions, can help establish workflows to advance new chemistries to enhance oil recovery.

This paper presents a study of fluids recovery stimulation agents that were formulated as surfactant blends or microemulsions. These microemulsions were formulated as Winsor Type IV systems that are optically transparent and thermodynamically stable solutions. These systems were tested with cores of various permeabilities using Amott cells. Spontaneous imbibition rates and oil recovery were investigated with a control and three surfactant-laden solutions. The surfactant imbibing capacity was also evaluated using computerized tomography (CT) imaging of the cores before, during, and after the imbibition process. The CT imaging of the cores was analyzed with other key testing parameters including surface tension, critical micelle concentration (CMC), and interfacial tension.

The results indicate that surfactant flow enhancing aids are desirable for improved oil recovery when compared to control fluid. The dependence of temperature and permeability on oil recovery was also investigated.

A methodology to evaluate imbibing capacity of aqueous fluids into formation cores saturated with crude oil was developed. The CT imaging was used to understand propagation of the liquid front inside the matrix. The statistical analysis of core-fluid interaction shows that core permeability has a significant effect on the rate of oil recovery.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018