Dewar Heat Shields
Protecting sensor electronics is an area of growing concern to oil and gas operators wishing to deploy high temperature logging systems, acoustic leak detectors and camera systems in HPHT downhole environments.
Severn Subsea Technologies (SST) has spent a number of years developing the heat shield technology needed to protect electronics circuit boards and camera systems from excessive heat downhole. Dewar heat shields are the perfect solution.
Based on Dewar flask technology, the heat shields comprise inner and outer stainless steel tubes insulated by a vacuum. The degree of heat shielding is project specific, with two primary solutions offered:
- Production of a thermal barrier to an agreed thermal resistance, and
- Production of a thermal barrier and modification of the digital signal processing (DSP) board to reduce its heat output, providing a tool with optimum heat resistance.
Severn Subsea Technologies offers heat shield thermal protection up to 400°C based on Dewar flasking technology. Dewars are available in three fundamental designs: Single open ended, Feedthru, and Hybrid.
Iceland Deep Drilling Project uses Dewar heat shields
The Iceland Deep Drilling Project (IDDP) is a project and consortium of the National Energy Authority of Iceland (Orkustofnun) and four of Iceland’s leading energy companies: Hitaveita Sudurnesja (HS), Landsvirkjun, Orkuveita Reykjavíkur and Mannvit Engineering. The consortium is referred to as ‘Deep Vision’.
The aim of the project is to look at the usefulness of supercritical hydrothermal fluids as an economic energy source. This meant drilling to depths of greater than 4,000 metres (13,000 ft) to reach temperatures of more than 400 °C (750 °F).
Severn Subsea Technologies (formerly Calidus Engineering) was asked to develop a memory based production logging tool capable of measuring pressure, temperature, flow rate and casing collar location at borehole temperatures up to 400°C. Unable to find a heat shield capable of withstand temperatures in excess of 250°C, we developed our own Dewar-based heat shielding system and was able to achieve 400°C. This experience has since been used by Severn Subsea Technologies in many HPHT projects.