Completion strategies and stimulation design are both vital to the performance of an oil well. In most cases these two are optimized, however, in many cases this is done separately. There are clear advantages to developing a completion strategy that includes the stimulation design. When the stimulation design is viewed as a "contingency plan" if the original completion strategy fails or is not optimized, the original completion can severely limit the stimulation design.
Real time diagnostics are used to evaluate two scenarios and compare only one of many issues relating to completion strategies and stimulation design.
Two similar wells in the Salem Formation were fractured using pretreatment diagnostics to aid in treatment design. Well No. 1 was produced for 3 1/2-years prior to fracture treatment recovering a total of 9400 bbl of oil. Well No. 2 was completed and fractured prior to any production. Included are results of prefracture diagnostics in both cases and production history of both cases. The purpose of this paper is to evaluate completion strategy, job size, and treatment diagnostic techniques in this field considering the production, pretreatment diagnostics, and treatment execution.
It is an agreed upon fact that the single most influential factor in fracture growth is the stress profile of the reservoir. This stress profile is influenced by the properties of the rock and of the pore fluids. The rock properties cannot be significantly effected, however, we can effect the pore fluid properties. The well can be produced to reduce the pore fluid pressure hence reducing the effective stress on the rock. Depending on the porosity, permeability, and the changes of these parameters with depth this process can drastically change fracture growth behavior.
Well No. 1. The first well treated was produced for 3 1/2-years prior to Fracture treatment recovering a total of 9400 bbl of oil. The reservoir pressure was reduced from 800 to 650 psi. This reduction in pressure should have created an additional 78 psi stress contrast between the productive layer and the boundary layers. The response of the prefrac treatment in this case was almost "textbook." A very clear closure could be seen and the decline was indicative of a contained fracture with leakoff characteristics of a classic wall building fluid. A forward simulation was run based on the diagnostic tests and the pump schedule was revised and pumped. P. 17^