LWD Formation Fluid Sampler Tool Collects First Fluid Samples While Drilling In Deep Water On The Norwegian Continental Shelf

Abstract

Fluid samples were acquired in an exploration well and subsequent pilot hole for an operator in deep water on the Norwegian continental shelf to identify the reservoir fluids and to check for potential connectivity between two reservoir targets. Several limiting factors meant that pipe-conveyed logging after drilling was not a viable option. Consequently, a logging while drilling (LWD) formation fluid sampling tool was run as a part of a LWD evaluation program to collect fluid samples while drilling and when pulling out of the hole after reaching TD (total depth) of the section. A team of global and local experts was established to plan the job. The team performed a risk analysis to identify risks and plan mitigating actions. Several challenges were identified, including the potential damage to equipment from vibration when drilling out the shoe track or from hitting stringers while drilling the formation. Other challenges identified involved potential tool movement from rig heave during sampling and required sampling time as a function of the duration of formation exposure to drilling mud before sampling. The team assessed the risks and established a plan to mitigate them, and the job was performed according to plan in February and March of 2014. A total of nine fluid samples were collected in two well sections, completing each section in one drilling run. This paper discusses the results of the third-party laboratory sample analysis. The formation evaluation logs were inconclusive as to whether or not the reservoir contained oil, condensate, or gas at some depths because of the laminated structure of the formation. The LWD fluid sampling technology confirmed that the reservoir contained gas. This paper also discusses the job planning, mitigating actions that were introduced, implementation and results of the job, and the benefits of fluid sampling while drilling.