Influence of various cation valence, salinity, pH and temperature on bentonite swelling behaviour

Abstract

Abstract.A major issue for the oil and gas industry is the producing of high water from many fields due to massive water injection. Reducing the water production while improving oil recovery from these fields is a major challenge. Polymer gel has been widely used to shut off water-producing zones, but it is not suitable for high temperature reservoirs (> 100 °C). The aims of the present study were to investigate bentonite particles swelling properties and influence of specific ion type (monovalent/divalent) present in water in swelling behaviour, and hence their potential for plugging high water production zones. In this study series of free swelling tests were conducted on bentonite with varying salinity, pH and temperature. The study found that cation valence, salinities and pH had significant impacts on swelling performance of bentonite particles. Bentonite changed from highly swelled material to aggregate in high salinity. Test results showed that the free swelling of bentonite decreased with the increase of cation valence and concentration. Monovalent cations concentration greatly influenced the swelling volume of bentonite, whereas the influence of the increasing concentration of divalent cations was marginal. As the radius of the hydrated ionic increased, the free swell of bentonite in same valance cation solutions raised. Moderate swelling changes were obtained when the solution pH increased. Meanwhile, increases in temperature will increase the swelling of bentonite due to growth in frequency of interlayer cations and water molecules. Bentonite particles swelling could be controlled and inhibited by varying solution salinities and/or altering interlayer exchangeable cations. Thus, bentonite particles swelling will be triggered by low salinity, after it's been injected and mixed with lower reservoir water salinity.

Graft Copolymerization of N-Isopropylacrylamide and Acrylic Acid on Bentonite Colloids for In-Depth Fluid Diversion

“…The free swelling of bentonite decreased with the increased of cation valence and concentration. The results confirmed that bentonite swelling properties could be controlled and inhibited by varying solution salinities and/or altering interlayer exchangeable cations . The particle size of the commercial API-grade bentonite that is normally utilized as part of drilling mud (<75 μ) is relatively bigger than the previously specified rock matrix diverting agents (<10 μ).…”

Experimental Setup for Evaluating Rock Volume Alteration and Its Application for Studying Shale Rock Swelling in Various Fluids

“…The experiment was performed using 0.2% wt. NaOH solution to increase the degree of bentonite swelling [39] Temperature and pump 2 pressure during the experiment were 110 °C and 23.6 MPa, respectively. The test results of this experiment are shown in Figure 3.…”

Volume change in compacted claystone-bentonite mixtures as affected by the swamp acidic water

“…This was due to the fact that the claystone samples were collected directly from the nature without any purification or other processes. Claystone is composed of various minerals, including kaolinite (1), illite (2,11), quartz (3,6,10,12,14,19), vermiculite (5,16), feldspar (7), montmorillonite (8,17), chlorite (9), mica (13), and kaolinite (15,18). In bentonite numerous minerals are found, including illite (2), feldspar (4), quartz (6), and montmorillonite (8,17).…”

“…The release of Al 3+ owing to fluids with pH of 2-6 was also observed in the study in which it resulted in the development of soil erosion. Meanwhile, Ahmed et al [10] found that the swelling ratio reduced when the pH in soil pores decreased due to acid water. Gratchev and Towhata [11] investigated the potential of changes in the compressibility of marine clay due to soil contamination from the past waste mismanagement.…”