Tight Gas reservoirs require fracturing as part of the reservoir exploitation strategy. The quality of perforations play an important role in establishing effective contact with the reservoir prior to fracturing. Several perforating technologies have been used and evaluated to optimize operations and saving completion costs. This practice has provided a wealth of data to analyze the most efficient strategy for tight gas reservoirs. An optimized perforating method has been implemented recently in fields that traditionally required hydraulic fracturing to bypass drilling damage and produce commercially.
Combining deep penetration charges with an instantaneous underbalance is the key ingredient for this method. The method results in achieving maximum reservoir contact, away from washouts, breakouts and damaged zone; thereby, delivering clean perforation tunnels and higher entrance hole diameter. In cases, where the productivity is limited by extremely low permeability and hydraulic fracturing becomes inevitable, the benefits extend to the fracturing operation in terms of lowering the breakdown and treatment pressures, improved treatment rates, effective proppant placement and minimizing the likelihood of pre-mature screen out. The paper outlines the detailed workflow including candidate recognition, treatment design, execution and evaluation leading to significant savings in operating expenditure. The paper also provides a comprehensive comparison with other perforating practices and evaluate their effectiveness.
The results obtained through deployment of this method on several wells are extremely encouraging. The wells were able to produce naturally, exceeding production expectations. As a result, significant time and cost savings were realized by eliminating subsequent production operations and well intervention work. The pressure transient analysis showed low skin pointing towards insignificant near wellbore damage.
This innovative method improves the way perforations are performed. Encouraged by this success, additional candidates are being evaluated with similar approach with an objective to optimize completion costs and improving initial production.