One-dimensional Swelling Behavior of Clay and Shale Under Electrical Potential Gradient

Abstract

Clay and shale formations are potentially subjected to swelling and softening when they are exposed to fresh water. Conventional swell test on clay and shale is very slow and it can take months or years to achieve the full swelling potential. This paper proposes the use of an electrical potential gradient applied across the clay sample to accelerate the swelling process. The fluid flow and ions transport in a clayey porous medium under an electrical potential gradient are examined along with possible chemical reactions. Details of the experimental design, setup, and testing procedures are presented. The test materials include reconstituted kalonite and bentonite samples saturated with sodium chloride solution and natural shale cores. Results of this study confirm that the applied electrical potential gradient enhances the ionic depletion and fluid flow, and subsequently the swelling process.

Interaction between Polymer-Based Drilling Fluids Containing Ordinary Salts and Clay Rocks

“…These problems are common and require expensive and time-consuming drilling and completion operations in the oil industry. Numerous studies show that wellbore instability problems cost 10% more in comparison to the cost of well construction, and exceed $1 billion according to [7][8][9].…”