Selection of high-rate gas well completion designs applying multi-criteria decision making and hierarchy methods

Abstract

Selecting the appropriate well completion design, equipment and installation techniques are frequent decisions required of oil and gas operators. Making selections from alternative completion designs can lead to enhanced well productivity, lower capital costs, less completion time and lower intervention/maintenance costs. However, typically there is a tradeoff of these benefits; with certain designs leading to lower costs and others leading to higher productivity or less risk of operational risks and costs. The decision often becomes a strategic one; imposing identified priorities of the operator upon the technical performance and cost assumptions made for each alternative. Multi-criteria decision-making methods (MCDM) offer a means of evaluating such decisions in a consistent and systematic way taking into account available information, assumptions and strategic preferences. MCDM is applied to three high-rate-gas-well-completion alternatives, i.e., mono bore (MB), big bore (BB) and optimized big bore (OBB), in order to aid the selection among them given certain strategic priorities. The MCDM techniques applied to gas-well-completion decisions are analytic hierarchy process (AHP) and technique for order of preference by similarity to ideal solution (TOPSIS). The criteria considered by these techniques include: time to run the completion, capital and operating costs involved, gas production rate achieved, and risk exposure associated with each well completion technique. The MCDM applied are particularly effective at providing insight to decisions when sensitivity analysis is conducted based upon different weights (i.e., strategic priorities) applied to the key technical attributes of the well completion alternatives.