Integrated reservoir fluid characterization in thinly laminated formations – A case study from deepwater Sabah

Author : Smail Chouya, John Jong, Janice Boay, Shota Nakatsuka, Samie Lee & Pascal Millot
Publication : Bulletin of the Geological Society of Malaysia
Page : 19-36
Volume Number : 65
Year : 2018

Bulletin of the Geological Society of Malaysia, Volume 65, June 2018, pp. 19 – 36

Integrated reservoir fluid characterization in thinly laminated
formations – A case study from deepwater Sabah

Smail Chouya1, John Jong2,*, Janice Boay2, Shota Nakatsuka2, Samie Lee1
& Pascal Millot1

1Schlumberger WTA Malaysia Sdn. Bhd.
2JX Nippon Oil and Gas Exploration (Deepwater Sabah) Limited
*Corresponding author email address:

Abstract: Reservoir properties such as fluid compositions, formation pressures, and fluid contacts are critical in the early phase of the well life and represent the key inputs for comprehensive production and reservoir engineering studies in the development phase. Accurate measurements and evaluations of reservoir fluid properties tend to become more
complex in challenging drilling environments, coupled with complicated reservoir facies such as the thinly laminated formations. To reduce the uncertainty in the estimations of hydrocarbon in place and fluid contacts in clastic reservoirs, it is paramount to integrate various measurements such as core data, log analysis, image logs, pressure data, and fluid
sampling results for a holistic and meaningful evaluation approach. Several methods are available nowadays for reservoir fluid characterization but each method has its own limitations and advantages. However, technical advancement achieved in individual technology alone may not necessarily provide a complete solution for the formation fluid evaluation task.
To reduce this uncertainty and to improve reservoir fluid evaluations, an integrated approach that combined various methods such as Advanced Mud Gas Logging (AMG), wireline Downhole Fluid Analysis (DFA) and PVT laboratory analysis is developed, based on a case study of an exploration well from deepwater Sabah. The integrated approach and workflow that combined these independent measurement methods proved to be the key to the success for formation fluid characterization. This paper is focused on how the integration of various methodologies can complement each other through the following strategies: assessment of reservoir fluid properties, starting from the early stages of open hole measurements, can be complemented by measurements obtained from AMG logging and wireline DFA and sampling. The AMG provides an early approach to reservoir fluid identification through its capability to generate a continuous fluid facies logged across the entire drilling interval. This study presents a successful case evaluation conducted for two drilling sections of the investigated exploration well. It demonstrates the strategies used for accurate fluid characterization assessments in a challenging deepwater environment, which is beneficial as a comparison for the subsurface assessment of other discoveries made in similar depositional setting.

Keywords: deepwater Sabah, fluid characterizations, petrophysics, thin laminations, wireline logs