Abstract
Sand-face completion technology for gas wells has evolved to overcome problems associated with sand and water production. Frac-packs, gravel packs, screens and oriented or selectively perforated completions have all been applied to gas wells to maintain wellbore integrity and control expected, late-life production challenges. However, none of these completion designs are capable of managing variable productivity, pressure or sanding tendency when producing multiple reservoir layers into a single wellbore. The result is premature water and (often) sand production. Intelligent completions employing Interval Control Valves (ICVs) can successfully manage these problems. However, not only are there limitations on the number of zones that can be separately controlled, but the hardware is also susceptible to the increased erosion potential of the high flow velocities associated with gas production.
Inflow Control Devices (ICDs) are an alternative Advanced Well Completion (AWC) technology. An ICD employs a passive flow restriction mounted on each joint of tubing or sand-control screen. The Autonomous Inflow Control Device (AICD) adds an "Active" water shut-off element to the flow equalisation provided by the standard ICD. An (A)ICD completion consists of multiple joints of (A)ICD equipped tubing separated into the required number of zones by Annular Flow Isolation (AFI). Such completions have the ability to equalise the gas inflow from many more layers (or even separate reservoirs) than is possible with an ICV or separated conventional completion.
This paper will present a critical evaluation of the ICD and AICD technologies together with a novel design methodology for their application to gas fields. This will be complemented by two case studies based on real data from both a gas and a gas- condensate field. These studies will be used to illustrate the application of the design workflow along with the potential advantages and added value derived by installing (A)ICD completions.
This design methodology and the field studies provide the basis for an extension of the (A)ICD's application envelope.
