A Novel Approach in Completing Unconventional Tight-Gas Condensate Wells Using Propellant Gas-Assist Perforating and Foam Matrix Acidizing: Case Study

Abstract

Abstract After successful production from a few wells in a California field, two development/appraisal wells were drilled targeting the southwest flank of the structure. Based on experience with the offsets, it was expected that this sandstone formation would be fracture stimulated to mitigate formation damage. Most of the wells in California have intervals ranging from 1,500 gross ft to ~600 net ft. Fracture stimulation or matrix acidizing are common stimulation techniques used on these types of wells. Fracture stimulation was attempted because of very low permeability but was not successful. On the first well, several attempts were made to establish fracture initiation in different intervals; however, on each attempt, the fracturing pressure encountered was too high to safely continue the job. A fracture gradient of more than 1.1 psi/ft was estimated. After 20 days of unsuccessful attempts, the operator ceased fracture stimulation of the well, which was nearing the point of abandonment because producing oil or gas did not seem economically viable at this point. After carefully studying the matrix rock, a gas-assisted perforating process followed by foamed matrix acidizing was recommended as an economical solution to produce the wells. This gas-assisted perforating process uses an extreme overbalanced (EOB) condition by using energized gas to simultaneously perforate and stimulate a well in a single intervention. During an EOB perforating application, wellbore pressures will exceed the fracture gradient for several seconds to minutes while injecting wellbore and tubing fluids at high rates. This paper presents a case study of two unconventional tight-gas condensate wells where using a gas-assisted perforating process followed by foamed acidizing provided successful stimulation. The design considerations, stimulation technique, and job details are discussed.