Innovative Use of Kaolinite in Downhole Scale Management: Squeeze-Life Enhancement and Water Shutoff

Abstract

Summary Applied research has been undertaken to examine the potential of kaolinite combined with a kaolinite-fixation agent to increase squeeze lifetime through alteration of near-wellbore surface characteristics and mineralogy, and to provide water-shutoff control. With respect to enhancing squeeze lifetime, it is documented that kaolinite increases the quantity of inhibitor adsorbed. Conversely, clean sandstone with low clay content commonly provides a poor substrate for adsorption. Furthermore, in reservoirs that experience near-wellbore formation damage because of kaolinite mobilization, it has been shown that the use of a fixation agent as part of a squeeze treatment can increase squeeze lifetime. Using these facts, research has assessed the feasibility of injecting microcrystalline kaolinite (average particle size 2 µm) combined with the fixation agent and scale inhibitor as a means of mechanically altering near-wellbore mineralogy and surface-property characteristics within clean, high-permeability sandstones. The testing has been designed to mimic the squeeze procedure used in the field for performing such a job and involves no additional steps to those used in a normal squeeze (i.e., Preflush, Main Treatment, Over-Flush). The paper presents the results of coreflood experiments that demonstrate "proof of concept," along with examples of potential field applications. A further concept, born from the initial idea, was the use of kaolinite and fixation agent for efficient, low-cost, environmentally friendly water shutoff. There are several available products for water shutoff, but the disadvantage of these is that they are not acceptable for use in Norway because of poor environmental characteristics. Hence, there was a need to fill this gap by developing water-shutoff technology to meet country-specific environmental legislation. The paper provides details of coreflood testing where an excess of kaolinite has been used to form an internal and external filter cake that is attached to the wellbore face and within the near-wellbore region using the fixation agent. The paper draws on data from StatoilHydro-operated fields in order to highlight the potential of this innovative approach to downhole scale management and water control.

Controlled releases of asphaltene inhibitors by nanoemulsions

“…Using high concentrations of inhibitor tends to produce self-associations in the bulk rather than adsorption on asphaltene, reducing their effectiveness [12,13]. More recently, attention has focused on increasing the effectiveness of inhibitors by increasing the adsorption of scale inhibitors on rock surface, hence increasing the lifetime of a squeeze treatment [14].These studies include: (i) mixing cations or Fe (II) ions with the scale inhibitor to provide better retention than using the inhibitor alone [15], (ii) adding pH modification chemicals to the inhibitor via a temperature dependent material such as urea, (iii) using mutual solvents (such as the small alkyl glycols) to change the rock wettability (more water wet) [16], and (iv) using kaolinite or other clay to enhance the inhibitor adsorption [17]. These studies, however, only showed limited reduction in the amount of inhibitors.…”

Advances of Nanotechnologies in Oil and Gas Industries

“…Squeeze lifetimes, and extension of such, are important for improving scale management. There are some researches trying to prolong the lifetime of a squeeze treatment by cross-linking inhibitors (Bache and Nilsson, 2000), enhancing additive's precipitation and adsorption (Rabaioli and Lockhart, 1996) or applying kaolinite to modify near wellbore surface properties (Fleming et al, 2009).…”