Multiwell pilots are the final step of enhanced oil recovery (EOR) screening before the final investment decision. Data gathering is the primary purpose of any pilot, including data about the reservoir’s response to the EOR method. A common technique for gathering data about spatial and temporal change in the reservoir resulting from injecting an EOR agent is time-lapse logging of an observation well positioned at some distance between the injectors and producers. Conventional observation wells are completed in cemented steel casing across the reservoir. However fiber-reinforced plastic (FRP) casing is used instead of steel when a more sophisticated logging suite is required. For example, induction resistivity, cross-well resistivity, and nuclear magnetic resonance are additional measurements that can be obtained if the casing material is nonconductive and nonmagnetic.

It is important to establish that the annulus ofany cemented well is hydraulically isolating. This is critical for an observation well in an EOR pilot to ensure that the well is notshort-circuiting the flow of injected fluids via annular channels. Cement evaluation of steel-cased wells has been a routine service since the 1950s, with at least four generations of tools developed to refine this measurement. Cement evaluation of FRP casing is experimental. Experiments were conducted to establish the operating envelope of an acoustic-based method of cement evaluation across a specific range of FRP casing wall thicknesses. These experiments were made to determine the optimal acquisition method for operating acoustic-based cement evaluation tools in FRP casing and to determine the optimum FRP casing wall thicknesses to acquire representative logs. The results from these experiments will be used together with the mechanical strength of the FRP to design the joints of casing that will be cemented across the reservoir for a number of EOR pilots.