Sand Production Potential Near Inclined Perforated Wellbores (1996)

Abstract Correct choice of perforation orientation in wells can either reduce risk of sanding initiation, or increase the possibility of massive sand production. This article presents a simplified approach to this evaluation procedure, based on stresses induced around perforation cavities in a cased wellbore. The effect of perforation orientation is shown to be a first-order component; therefore, along with other factors such as draw-down rate and charge size and density, such a procedure should be incorporated into sanding evaluation. INTRODUCTION Solids production is a negative aspect of high-rate oil or gas production from weak reservoir rocks. By contrast, massive solids production in viscous heavy oils found in unconsolidated strata is highly beneficial in increasing production rates. In the former case, well completion strategies and production practices are implemented to reduce the incidence of deleterious solids influx: the goal is exclusion while maintaining acceptable production. In the latter case, practices are implemented to keep sand flowing into the hole to maintain the enhanced production (often by a factor of 10 or more): the goal is maximum production, along with sand management Aspects of optimization and risk enter into both cases. To achieve an economic completions strategy compatible with production rates, one must understand the mechanisms involved, carry out analyses which capture the key factors which contribute to solids and fluids production, and come up with acceptable engineering solutions. Smith (1988) discussed possible mechanisms involved in massive solids production, focusing on the fluid flow aspects. Dusseault and Santarelli (1989) also addressed the mechanisms involved in massive continuous solids production, focusing on geomechanical aspects. This work has recently been approximately quantified, based on the concept ()f stress- and flow-induced liquefaction of the unconsolidated sand fabric (Geilikman et al., 1994; 1995). To confirm these models and ultimately develop a practical tool for sand management, field data are considered to be vital. Most published articles involve case history documentation and ameliorative procedures, usually for sand exclusion, often combined with a method of analysis (e.g.: Durrett et al., 1977; Morita et al., 1987; Santarelli et al., 1991; Morita et al., 1991; Weingarten and Perkins, 1992; Moricca et al., 1994b; Ramos et al., 1994). Limited experimental data are also available for all types of solids production in order to quantitively define the sand production processes (Tronvoll et al., 1992; Kocijrnan et al., 1992; Tronvoll and Halleck, 1994; Yim et al., 1994). Yet other studies involve only development of methods of analysis to model sand production initiation. Erath and Risnes (1981) proposed a quantitative isothermal criterion for solids production initiation using a Mohr-Coulomb yield criterion and a spherical cavity in an isotropic stress field. Similar approaches for cylindrical cavities, intended for borehole stability (Wang and Dusseanlt, 1991), apply the analysis for unconsolidated sandstones into elastoplastic cases and non-isothermal conditions characteristic of heavy oil reservoirs (Wang and Dusseault, 1995; Wang, 1995). Weingarten and Perkins (1995) extend similar approaches into gas production cases. All these studies, however, are strictly limited to a 2-D vertical well case subjected to a uniformly distributed stress.