Abstract

Maximizing productivity from every well has always been the ultimate objective of industry experts. Connecting the wellbore with the reservoir is a key element towards meeting this challenge. In the case of perforated completions, techniques like static and dynamic underbalance are used to try and remove the crushed zone caused by the perforation process. In marginal reservoirs, poor connectivity can be the difference between a commercial discovery and a dry well.

Reactive liner perforation technology is a new technique which removes the crushed zone using a highly exothermic reaction, providing a step-change improvement in perforation geometry and performance. The reaction breaks up and expels debris to leave a clean, undamaged tunnel, even in variable or low quality rock. This process is independent of lithology and wellbore conditions. This next generation perforating technique has recently been launched in Pakistan with exceptional results.

This paper describes these successes in greater detail. When compared with offset wells with identical parameters, perforated using relatively new techniques, the superiority of the reactive technique was proven. Significant rate improvements and very low (negative in some cases) values of total skin were measured. When applied prior to hydraulic fracturing, significantly reduced initiation pressures and lower horsepower requirement added significant value through optimized fracturing treatment, reduced risk of screen-out, and reduced expenditure.

Results in-hand prove the superiority of this technology in improving well connectivity, particularly in tight gas reservoirs. The independency from rock properties and wellbore conditions are truly added advantages of the reactive liner technology. This is a technically viable and cost efficient option for ensuring operators achieves their production objectives.

Introduction

Achieving optimum well productivity depends on effective connectivity to the reservoir. Poor connectivity will not only have a detrimental effect on the well production but will increase the completion and operating cost of the well due to additional remedial treatments and interventions required to improve the well production. Poor connectivity can lead to incorrect diagnosis of the reservoir's true potential which can affect the operator decision if the well is commercially viable for production or if it is to be plugged and abandoned.

In cased and perforated completions, perforating techniques are used to provide a conduit for the inflow of hydrocarbons or injection points for injectants. Since its introduction in 1950s, shaped charge perforators have been the dominant perforating method. The shaped charges employ an explosive cavity effect coupled with a metal liner to maximize penetration. Once the main explosive is detonated, the liner collapses to form a high-velocity jet that is propelled outward at approximately 30,000ft/sec. The shaped charge deployment simplicity is its main advantage and over the years, new developments in shaped charge perforations have allowed operators to create deeper perforation tunnels. Achieving maximum penetration depth is important as it contributes to the effective wellbore radius, however the main factor which leads to optimum well flow performance is the quality of the perforation tunnel. Shooting so deep requires a violent and damaging event, where the rock surrounding the tunnel is deformed far beyond its plastic limit and smashed rock fragments are driven into the adjacent pore throats (Bell 2009). This so called "crushed zone" is almost impermeable to flow. In addition, the compacted fill at the tip of the tunnel and debris remaining in the tunnel further contributes to inefficiency of the perforation.

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