Summary
Data acquisition in extreme environments of high pressure and/or high temperature (HPHT) with pressures up to 30,000 psi and temperatures up to 500°F requires not only specialist technology capable of surviving these conditions but also many months of preparation and planning to ensure a successful operation.
The aim of this publication is to provide an overview of what is involved in the planning, preparation, and execution of an extreme HPHT wireline data acquisition—from the customer setting the information objectives through to data delivery. This includes developing an agreed quality plan between the data provider and the customer covering testing and deployment of the latest extreme HPHT logging equipment.
One must consider all aspects to minimize risks including detailed tailoring of the logging programs to manage time in hole, to ensure accurate depth control, and, by using a deployment risk-management process, to ensure that what goes in the hole comes out again.
The implementation of these procedures is illustrated with a case history of a series of HPHT exploration wells drilled in the Central Graben of the North Sea (the "HPHT Heartland" of the North Sea). Bottomhole conditions were predicted to approach 400°F and 15,000 psi. These extreme conditions negated the use of conventional wireline tools, and so, from initial early planning discussions between client and service provider, new detailed programs were designed and implemented as a specific "Quality Plan" to use the advanced HPHT wireline-logging tools.
