Slotted liners used for primary heavy oil recovery support relatively minor operational loads at the depths and pressures common in Western Canada. In such applications, installation loading is the primary concern, and load limits can be defined using an elastic design basis to support running operations. In thermal operations, the installation limits need to be more stringent, because of the impact of residual stresses and deformation on the operating response. Furthermore, the high axial loads induced by confined thermal expansion can place the liner into large-scale yield, where localization resistance is virtually eliminated and a variety of deformation failure mechanisms can become manifest. A prudent design takes the deformation mechanisms into consideration, balancing the mechanical requirements for supporting thermally-induced loads against the inflow requirements to generate the final design.

Commercial Steam Assisted Gravity Drainage (SAGD) projects currently under development in Northern Alberta typically use slotted liner for both injectors and producers. Reservoir sand grain size distributions and inflow requirements require slot densities as high as possible without compromising the structural integrity of the wells. Therefore, a design assessment was required to determine the relationship between slot geometry and density, thermal and production loading, and post-yield material properties. A variety of possible failure mechanisms were considered, and failure limits in terms of these controlling parameters were evaluated. The outcome was an allowable slot density, slot geometry and post-yield material description required for the liner to operate reliably, and corresponding quality assurance programs to ensure the slots and material satisfy the requirements for reliable operation.

You can access this article if you purchase or spend a download.