Development of a Viscosified Scale Inhibitor for Improving Placement in Acid Fractured Limestone Reservoirs

Abstract

Scale is a major problem for the oil and gas industry and is often controlled by the use of downhole scale inhibitor squeeze treatments. The placement of scale inhibitor in acid fractured limestone reservoirs presents a particular challenge and effective placement of scale inhibitor cannot be guaranteed when performing conventional low rate (<10bpm) bullhead squeeze treatments. In order to ensure the fluid package is placed over the whole of fractured interval it is necessary to perform high rate scale squeezes (40–60bpm) in conjunction with mechanical divertors. However, these treatments are expensive and limit the amount to treatments that can be performed per day in a scale squeeze campaign. This paper describes the development of a range of viscosified polymeric scale inhibitors for squeeze application in acid fractured wells. A particular feature of these products is their viscous self diverting nature which means they can be used at low pump rates at rates of <10bpm. This method also precludes the use of mechanical divertors and enables cross flow problems to be overcome and effective chemical placement over the whole of fractured interval. In addition, this offers the benefit of improved scale control and squeeze lifetimes coupled to considerable economic savings by being able to perform more treatments per day using conventional pumping equipment. A detailed investigation into the rheological properties of selected products has been performed to design the optimal delivery system. Experimental data on the compatibility of a variety of viscosifying agents and chemical breakers different types of polymeric scale inhibitors will be presented. This will include viscosity profiles, shear thinning behavior and breaking times for these systems. Inhibitor performance and core flood studies to evaluate formation damage potential and retention and release characteristics will be also be presented. In addition, the paper will add the results of a computer modelling study to validate the experimental data and aid the placement strategy for optimum field application. Introduction Oilfield scale is a key issue in the petroleum industry where vast amounts of water are used and co-produced with hydrocarbons. The formation of mineral scale can create a range of problems including; reduction in pipe carrying capacity, increase in operational hazards due to blocked valves, localization of corrosion attack, impedance of heat transfer, and increases in operating costs due to down time and system maintenance.

Boehmite Based Sulphonated Polymer Nanoparticles with ImprovedSqueeze Performance for Deepwater Scale Control

“…In order to better control the placement of scale inhibitor, viscous fluids with both Newtonian and non-Newtonian properties were studied experimentally and theoretically in the last decades (Selle, et al 2009;Sorbie, et al 2006;Heath, et al 2008). In order to better control the placement of scale inhibitor, viscous fluids with both Newtonian and non-Newtonian properties were studied experimentally and theoretically in the last decades (Selle, et al 2009;Sorbie, et al 2006;Heath, et al 2008).…”

Synthesis and Sorption Study of AlOOH Nanoparticle Cross-Linked Polymeric Scale Inhibitors and their Squeeze Performance in Porous Media

“…Viscous fluids with both Newtonian and non-Newtonian properties were investigated experimentally and theoretically in the last decades to better control their placement (Selle, et al 2009;Sorbie, et al 2006;Heath, et al 2008). Simulation of applying shear-thinning inhibitor slug showed dramatic effects on inhibitor placement in a linear heterogeneous system (Sorbie, et al 2006).…”