Clay Minerals – Mineralogy and Phenomenon of Clay Swelling in Oil & Gas Industry

Abstract

Among the minerals found in the earth's crust, clay minerals are of the widest interest. Due to the specific properties such as plasticity, absorbing and catalytic properties clay minerals are used in many industries (oil & gas, chemistry, pharmacy, refractory technology, ceramics etc.). In drilling, a phenomenon of swelling clays is frequently observed. It has an important impact on the cementing quality. During the last few decades clays have been the subject of research on a scale unprecedented in the history of mineralogy. This paper presents review literature on mineralogy of clay minerals and phenomenon of swelling in oil and gas industry. Unique ion exchange properties and clay swelling mechanisms are also considered.

Drilling Fluids for Deepwater Fields: An Overview

“…Most of these shales are relatively unreactive but some of them can hydrate and slough [11,18]. Table 1 shows also properties of smectite minerals which present higher adsorptive capacity (cation exchange capacity = 80-150 meq/100 g), indicating higher reactivity and swelling potential as it has been widely reported in literature [11][12][13][14][15][16][17][18]20]. Smectite minerals include a variety of clays such as montmorillonite, hectorite, and beidellite.…”

“…Generally, geological formations found in deepwater fields are relatively young and very reactive [11][12][13][14][15]. In this way, it is generally accepted that highly reactive shale formations are intrinsic to deepwater drilling, where their interaction with drilling fluids is the main factor in wellbore instability, which is considered one of the major causes of troubles, waste of time, and over costs during drilling [16][17][18]. In this way, problematic shales are responsible to origin more than 90% of wellbore instability problems [18].…”

“…In this way, it is generally accepted that highly reactive shale formations are intrinsic to deepwater drilling, where their interaction with drilling fluids is the main factor in wellbore instability, which is considered one of the major causes of troubles, waste of time, and over costs during drilling [16][17][18]. In this way, problematic shales are responsible to origin more than 90% of wellbore instability problems [18]. Moreover, it has been reported that shales (principally clays) represent 75% of all formations drilled by the oil and gas industry [16].…”

“…Their main characteristics have been reported [11,21] and are shown in Table 1 Kaolinite is commonly considered as a highly stable mineral clay, non-swelling, presenting a relatively small surface area and a low adsorptive capacity (cation exchange capacity (CEC) = 3-10 meq/100 g) as shown in Table 1. Kaolinite clay can be easily dispersed in water-base drilling fluids [11,18]. Chlorite mineral is generally considered as non-swelling clay.…”

“…The process is thermodynamically comparable to phase transitions. Several water-molecules layers may line up in order to build a quasi-crystalline structure between unit layers, resulting in an increased interlayer spacing [15,18]. The principal action force of this mechanism is the adsorption energy of water on the surface of clays.…”