The main focus of any perforation system is to establish effective hydraulic communication between the wellbore and the reservoir. A primary attribute for this connection is maximum penetration in the undamaged reservoir rock, especially in mature and highly depleted reservoirs. Drilling and completion fluids cause a certain amount of damage in the near well bore region, the perforating tunnels must bypass the damaged region to create the effective flow path and enable maximum well productivity. The challenge is to create a deep, clean, undamaged tunnel to maximize oil and gas production from the reservoir.
A new Triple-Jet™ perforating system was recently introduced in the North Sea, and it uses the existing shaped charges and a slightly-modified hollow steel carrier as from those currently used in the industry. This system provides a new perforating concept that exploits the beneficial aspects of firing a bank of three co-linear focused charges into the formation. The jets from the upper and lower perforating charges are angled to intersect within the formation, while the jet from the center charge is slightly delayed such that its perforating tunnel has the benefit of penetrating the tensile-stress-altered rock within the formation. The resulting shock wave from the converging jets produces a proportionally smaller crushed zone and weakened material around the perforation tunnel that is easily removed by low underbalance methods. Simulated downhole testing conditions show that this system significantly improves both penetration and flow performance and provides potentially greater well productivity than the same charges loaded in a traditional hollow steel carrier with similar charge-to- charge phasing angle. Because the Triple-Jet system produces weakened rock that is easily removed by low underbalance, it is ideal for both new well completions and re-perforating existing wells.
The new perforating technology complies with similar safety standards as conventional perforating systems, raises no additional issues with explosives licensing, guns are run and fired in the conventional manner, and does not require substantial new work or training for the crew or platform management. This paper compiles a series of laboratory experiments that are modeled with an analytical simulator and provides a brief description of the job-field application.