Well-Performance Calculations for Artificial-Lift Screening
Authors: Wilson Adam 
Published: July 2017

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 181344, “Well-Performance Calculations for Artificial-Lift Screening,” by P.A. Kefford, SPE, and M. Gaurav, Integrated Production Technologies, prepared for the 2016 SPE Annual Technical Conference and Exhibition, Dubai, 26–28 September. The paper has not been peer reviewed.

Having the means to evaluate different forms of artificial lift efficiently early in the planning cycle significantly improves the ability to influence other planning decisions such as well count, well design, and facility capacities and to realize the potential benefits made available by new artificial-lift technologies. This paper focuses on a fit-for-purpose methodology to evaluate well-production performance for a wide range of artificial-lift techniques.

Introduction

In a typical artificial-lift selection process, the first stage, screening, involves considering a wide range of artificial-lift techniques and their suitability regarding fluid types, reservoir properties, and operating environment. Once a short list of feasible lift techniques is determined, a more-in-depth comparison of these options is undertaken by forecasting the performance over the life of the field. Options for generating such forecasts range from simple spreadsheet calculations to fully integrated asset models coupling detailed reservoir, well, and facilities models. The choice of forecasting technology depends largely on the field size and complexity. The next step is to perform an economic analysis to guide the ultimate selection of the preferred lift techniques. The economic analysis ac-counts for the capital and operational expenditure associated with each lift technique and uses the production profile to generate net-present-value estimates.

The initial screening of artificial-lift technologies involves consideration of multiple criteria that will have varying degrees of significance depending on the specific reservoir properties and operating environment. Common artificial-lift screening criteria are

Well productivity

Operability

Environmental effects

Solids handling

Well-design compatibility

Flow assurance

Reliability

Gas handling

Facilities requirements

Power requirements

Temperature limits

Reservoir access

Local knowledge/support

New-technology risk

Workover cost

This paper focuses on the screening criteria related to a well’s hydraulic performance—namely, well productivity, gas-handling ability, and power requirements. Understanding what production rates are achievable with each lift technique in a particular environment, and knowing the interdependency these have with well count, well design, and facility capacities, is key to maximizing asset value. Equally important, quantifying how the free-gas volume entering artificial-lift equipment varies with drawdown and depth, and how this relates to the gas-handling capacity of the artificial-lift equipment, is necessary to ensure reliable operations without unduly constraining production. Finally, the power requirements have a direct effect on operational expenditures and, therefore, are important to quantify.