Perforating Multiple Sands With Long Interval Separations Pushes The Limit In Completion Efficiency
Authors: Ene Emeka , Fagbami Debo , Chiedu Onyeka , Benjamins Comfort , Akudolu Nnamdi , Nwajei Anthony 
Published: July 2015

The fate of a well hinges on years of exploration, months of well planning and weeks of drilling. But it ultimately depends upon performing optimal completion, which begins with the second of performing millisecond of perforation. Perforation forms conduit into the reservoir thereby giving access-way for hydrocarbon recovery and well production and optimization. Based on well profiling, we find out that some wells have single sands while some others have multiple sands which could be quite a considerable distance apart. The mundane perforation practice in the industry has been quite painstaking in carrying out several trips in archieving multiple sand perforation but the advent of innovation and technology has been such that a means of perforating several sands in one run has been devised.

The normal perforation practice in the industry is usually to carry out multiple trips to perforate intervals above 200ft apart either by wireline or by Tubing conveyed Perforation. Such Techniques only adds to increased cost and time to the completion time. This also adds some form of inefficiency of the perforation tunnels due to damage of the near wellbore from completion fluids and pressure surges between the two perforation runs.

This paper highlights an approach to deploying a single trip multi-zone TCP system.

The strategy is based on a multi firing system that allows for selective loading and firing of guns for several intervals without using the continuous gun spacers. This paper described in detail the innovative technique of perforating multiple intervals in a single run.

This technique was recently applied successfully in an oil well in Nigeria. The pay-zones were 700ft apart. The initial consideration was to either use the Wireline conveyed perforation technique or using the Tubing conveyed perforation method in multiple runs. These methods would have been costly and time consuming.

The paper focused on three major technical contributions to the oil and gas industry. Firstly, it documents successful application of multiple guns in a single run. Secondly, it describes the design considerations involved as well as the calculation required to safely design the multiple gun run in one trip. Thirdly, it identifies a technique of perforating multiple zones without exposing the earlier perforations to risk of formation damage by shooting the entire interval in one go.

The key areas of concern when designing the perforating technique were being able to correlate the lower zone at depth with the RA marker 800ft above the lower gun assembly and the combined detonation pressures. Both of these factors were carefully handled by strapping all components thoroughly, using known length of drill pipe pup joints and use of time delay multi firing system respectively.

Perforation design is now an integral, customized element of Completion planning; it addresses the efficiency and optimization of the Completion process of a well, with a focus on enhancing Positive Net Present Value of Operators' investment especially at the completion stage, all these done considering the peculiarity of the well. This paper describes a field proven technique deployed to perforate multiple zones in a single trip in hole using drill pipe to space out the different zones. This technique is made possible by utilizing Sequential Multi-Fire system with bottom line of cost savings and efficient operations.