Learning from lessons in downhole gauges as part of a well optimisation strategy

Abstract

Downhole gauges are designed to operate in a harsh working environment and are commonly installed in conjunction with a progressing cavity (PC) pump. They measure the pressure at or slightly above the PC pump and, along with a casing pressure gauge, they can be used to measure the fluid level in the well. An understanding of the fluid level in a well allows the operator to control the well drawdown process and protect the PC pump if it is installed with a well optimisation system that can maintain the desired water level or stop the pump if required. Downhole gauges provide valuable data for reservoir analysis and well planning, especially for low-perm coals. They are often criticised for failing, but root cause analysis often finds that failure is not the gauge, rather it is caused by other components of the well completion. This extended abstract discusses the operational experience and analysis of operating downhole gauges across a 10-year period while working with several gas companies in Queensland, NSW and China. In these locations different cable-type downhole gauges, such as a low-density polyethylene (LPDE) sheathed, armoured cables and solid tubular stainless steel cables, were fixed to the tubing. This knowledge can extend the working life of downhole gauges and help operators develop well optimisation strategies.