Laboratory Investigation on Gelation Behavior of Xanthan Crosslinked With Borate Intended to Combat Lost Circulation

Abstract

Crosslinked polymer gels have been extensively used in upstream petroleum industry for water shut-off, profile modification and hydraulic fracturing. The successful history of those applications has led to opening of a new frontier for solving one of the most severe and costly drilling problems known as lost circulation. Xanthan chains can be crosslinked by borate ions released from borax in appropriate pH conditions and consequently convert to a three-dimensional gel structure that can block thief zones. Steady shear viscometry method was applied in which the gel system was under constant shear rate while apparent viscosity had been recording. Apparent viscosity is almost constant up to initial gelation time in which viscosity starts growing up. Initial and final gelation times, initial and final viscosities are parameters that can describe the behavior of a gel system and are reported in this paper. The effects of concentrations of xanthan blended with borax, a pH-controller, and magnesium chloride as well as mixing time, shear history and temperature were investigated. Moreover empirical models are suggested for prediction of initial and final gelation times/viscosities as a function of the above-mentioned variables. Although the initial gelation time decreases when mixing periods increases, the summation of those is constant. In other words, the reaction causing gelation cannot be postponed by mixing. This is also true when the gel is at rest. On the other hand, it was observed that gels with high-shear rate history demonstrate similar initial gelation time as gels under 3 rpm steady shear. Moreover this low shear rate was found to not interfere in initial gelation time. Temperature and pH-controller reduce the time required for initiation of gelation. Magnesium chloride reduces the viscosity. Consequently the final gel is weaker and occurs in a longer time. Xanthan blended with borax contributes to the system mainly by increasing the viscosity. Finally the empirical models can be used to manage lost circulation treatment job. They help to have enough time to pump the pill with a known viscosity and wait enough on a gel with a desired quality.

Research on the Functional Microbe Activation System in a Post-Polymer Flooded Reservoir

“…These disparities in microbial communities inevitably affect the screening of subsequent activators and the evaluation of their effectiveness. Consequently, conducting analyses of indigenous microbial communities in various types of oil reservoirs, clarifying the characteristics of these reservoir microbial communities, identifying their predominant oil displacement functional bacteria, and subsequently formulating targeted activation strategies for these functional microorganisms is imperative for designing efficient technologies for MEOR [37,38]. Studies have shown that nutrient-rich environments favor fast-growing bacteria, whereas nutrient scarcity selects bacteria with efficient nutrient utilization.…”

“…cient technologies for MEOR [37,38]. Studies have shown that nutrient-rich environments favor fast-growing bacteria, whereas nutrient scarcity selects bacteria with efficient nutrient utilization.…”

Effect of Polymer and Crosslinker Concentration on Static and Dynamic Gelation Behavior of Phenolic Resin Hydrogel

“…The initial gelation time refers to the moment when the viscosity of the system begins to significantly increase at the beginning of the cross-linking reaction. The final gelation time is the time when the system viscosity reaches stability at the end of the cross-linking reaction [25]. The initial gelation time and final gelation time with different formulations of hydrogels can be obtained from the curves in Figure 3.…”

Dynamic and static gelation behavior of phenol formaldehyde resin gel system in ampoule bottles and porous media

“…IGT is the time of sudden increase in viscosity. FGT is the time of nearly finish reaction (Mokhtari and Ozbayoglu, 2010). The results of gelation time of different concentrations were shown in Figure 2.…”