Perforating Techniques for Maximizing Well Productivity

Abstract

A major objective of any well completion is to attain maximum production. The perforating equipment and production. The perforating equipment and techniques that are used have a very important bearing on determining the production that results. production that results. According to the nature of the reservoir, wells may be completed either naturally, with sand-control measures, or with formation stimulation by acidization and/or hydraulic fracturing. The wellbore-to-formation pressure relationship at the time of perforating may be overbalanced, balanced, or underbalanced. Perforating guns may be retrievable, Perforating guns may be retrievable, semi-expendable, or expendable; designed for operation through tubing or in open casing; run on wireline or on tubing. This paper describes the various combinations of guns and techniques that are in common use, with the advantages and disadvantages of each. The four basic performance parameters, i.e., shot performance parameters, i.e., shot density, perforation diameter, penetration depth, and gun phasing, are ranked in order of relative importance for natural, sand-control, and stimulated completions. Where justified, the author makes recommendations and draws conclusions. Introduction Perforating techniques to get best well productivity depend on the type of well completion; i.e., natural flow, sand control, or hydraulically fractured. Even within a particular completion method, choices of technique and equipment are constrained by the well configuration, wellbore fluid type, pressure, formation characteristics, and damage conditions. In general, the objective is to perforate in a way that produces minimum perforate in a way that produces minimum resistance to flow at the reservoir/perforated-system interface. This can be done by:–establishing well conditions that enhance cleanup of the perforations, and–choosing perforators and techniques for best flow performance. The intent of this paper is to describe the nature of the choices to be made, to discuss some of the factors that bear on these choices, and where justified, to make recommendations and draw conclusions as to the appropriate action. NATURAL COMPLETIONS The natural completion involves formations that do not require artificial alteration to permit worthwhile hydrocarbon production. This definition thus excludes completions requiring stimulation by fracturing or massive acidization, as well as those requiring gravel-packing or sand-consolidation treatment. Not excluded, however, are wells that are lightly treated with "mud acid" to cope with wellbore damage. Ideally, the well is perforated and placed directly on production. placed directly on production.

Perforation Design Models for Heterogeneous, Multiphase Flow

“…......... (3) where P RBI is the single phase factor computed from Equation (2) but with the following definition of quantities: q = oil flow rate at reservoir conditions, ft 3 /day J.L = oil viscosity of fluid, cp k = permeability to oil ko = kk ro , md…”

“…Significant benefits can be obtained from the optimization of perforating in terms of reducing the cost of new completions or improving productivity of existing wells [2,3]. The existing design techniques are based on laboratory work [4], analytical techniques [2], and mathematical modelling [5,6].…”

An optimal model for predicting the productivity of perforated vertical HTHP wells

“…In reality, available perforating technologies are far more distinctive than just punching holes. Not only is there a marked performance difference between commodity and premium shaped charges, but also optimisation for a specific application can obtain a further 10–20% improvement in both penetration and productivity …”