Taming Complexities of Coupled Geomechanics in Rock Testing: From Assessing Reservoir Compaction to Analyzing Stability of Expandable Sand Screens and Solid Tubulars

Summary Well geomechanics and "smart" completion designs in many of Saudi Aramco's fields are essential in supporting the company's efforts to apply the extended-reach and MRC well technologies. MRC wells are being aggressively targeted to optimize development economics, enhance recovery, maximize production, minimize differential drawdown across the sand face, reduce sanding potential, and defer water coning. In addition, many unconsolidated sandstone reservoirs require positive sand-control measures. As such, Expandable Sand Screen (ESS) tubulars have seen a recent surge in applicability for completing conventional and MRC wells in sand-prone, troublesome formations. Today, solid expandable tubulars are being tested on a number of wells in a pseudo-monodiameter structure. Though attractive, the long-term performance of these tools in the Arabian Reservoir environments is yet to be explored. This paper simulates the impact of reservoir production and depletion on expandable tubulars and sand-screen completions when the compacting reservoir behaves as a permeable poroelastic medium. A general poroelastic solution model encompassing a multitude of boundary and initial conditions is discussed in this paper. The model simulates the uniaxial (Ko) testing of solid and hollow geomaterial cylinders (Geertsma 2005). Thus, it helps infer about potential problems that might influence the survivability of "expandables" and disrupt the outflow from the well. The proof cases on reservoir and caprocks presented herein are supported with numerical application, experimental validation, and physical interpretation of the coupled poromechanical processes that are reflected in the anisotropic, time-dependent rock responses during testing. The manuscript also demonstrates that this enhanced approach to modeling visualization will ultimately ease the tractability of the pertinent physical phenomena as well as support the model's computational credibility to engineers and experimentalists in the oil and gas industry. Introduction Many applications in our industry take place in fluid-saturated rocks that exhibit rock matrix anisotropy due to their mode of geological deposition or diagenesis. These applications are commonly subjected to nonisothermal conditions. The theory of anisotropic poroelasticity was developed by Biot (1955), improved by Biot and Willis (1957), and reformulated with applications to civil and petroleum engineering problems by Thompson and Willis (1991) and Abousleiman and Cui (2000), among others. The reformulation of the anisotropic poroelastic theory while using laboratory techniques for the measurements of the anisotropic poromechanical parameters (Scott and Abousleiman 2002) had been of great help in assessing the effects of the parameters anisotropy in a few of the engineering applications. These applications included, for example, borehole and cylinder analyses (Abousleiman and Cui 1998; Kanj et al. 2003) and the Mandel problem (Abousleiman et al. 1996). Sherwood (1993) proposed a modification of the Biot theory of poroelasticity (Biot 1941) to include the chemical potentials of all chemical species, within the pore fluid. Within this context, Sherwood and Bailey (1994) conducted an axisymmetric, plane-strain analysis of shale swelling around a wellbore and extended it to include the case of a finite hollow-cylindrical shale sample being subjected to a hydrostatic state of stress. In a more rigorous approach, chemical effects can be addressed by considering the pore fluid to comprise two constituents, solute and solvent, and appropriately accounting for the solute and solvent transport in and out of the porous matrix (Sherwood 1994; Ekbote and Abousleiman 2005).