Formation Evaluation Society of Malaysia (FESM)

Formation Evaluation Society of Malaysia (FESM)

​Title : A "Boomerang workflow for geological & petrophysical characterization of the shaly heterolithic reservoirs in offshore Brunei."

​To provide technical justifications to the log-based reservoir facies classification and porosity quantification in the transitional shoreface sandstones and shales, this article presents a collective, sequential and integrated analysis scheme called Boomerang method based on the observation of the log response and core calibration across the offshore Brunei oil and gas fields. The new reservoir net-to-gross and porosity quantification tested in multiple core wells suggest that the thin-beds and heterolithic rocks cut-off by the default Vsh approach may contain significant amount hydrocarbon volume.

The gradual coarsening upward offshore-to-shoreface parasequences collectively display boomerang-looking distributions on log crossplots. The boomerang inflexion marks the boundary between the shaly and the sandy lithology. Based on calibrations with cores and borehole images, thin-bed and heterolithic rocks commonly found in lower shoreface to offshore transition and tidal environments correlate to the bottom part of the sandstone boomerang wing near the inflection.The boomerang characters are mainly related to combined effect of sedimentary process, compaction and pore fluid property. Without hydrocarbon effect, the shoreface parasequences in a similar environment make similar boomerangs. Systematic catalog of the boomerangs across offshore Brunei provides collective lithology reference to enhance the signatures of different hydrocarbons, particularly in the shaly heterolithic or thin-bed reservoirs where fluid responses may be over-whelmed by the high shale content. A computer program is developed to interactively define the boomerang sequences, determine hydrocarbon zones and pick the key boomerang points in multiple crossplots. A dual fluid model is used to compute total and effective porosities from neutron density crossplots in different sequences and fluids.

Bio data: 
Chunming Xu – Geoscience Discipline Advisor, Brunei Shell Petroleum

Chunming Xu has more than 35 years of experience in conventional and unconventional oil and gas in variety of geological settings around the world as a geologist or exploration geoscientist. Since he joined Shell in 2006, his has put a lot of effort in the seamless integration of petrophysics and geology in characterizing complex reservoirs such as the heterolithics and thin-beds in shoreface and deepwater environments. As the Subject Matter Expert for borehole imaging (BHI) technologies in Shell, he has carried out and published numerous BHI case studies for calibrated structural and stratigraphic interpretation of fluvial, lacustrine, shoreline and deepwater sediments by integrating borehole images, open-hole logs, cores, seismic and outcrops.

Prior to Shell, he worked as a borehole geologist for Schlumberger and an exploration geoscientist for PetroChina. He received B.S. in Geosceince in 1982 from Jianghan Petroleum College, China.