Delineation of reservoir lateral continuity for flow zones in wells using cluster analysis: Case of West Baram Delta, offshore-Sarawak

Abstract

Reservoir property modeling is often used to determine lateral extent and continuity in targeted multiple wells for implementation of any enhanced oil recovery (EOR) methods. Some works were reported that most of EOR techniques are controlled by static-dynamic lateral extent and continuity within reservoir pay zones succession as they contribute to poor recovery in fields. Therefore, delineation of lateral extent and continuity using a statistical approach could save time, less cumbersome and data required. This paper by cluster analysis delineates lateral extent of 5 exploratory wells by integration of microscopic petrographic and petrophysical data from 132 subsurface and 97 core plugs. Result reveal four main petrofacies clusters of good lateral extent and continuity that corresponds to section (Blue cluster) characterized by massive coarse grained sandstones, massive fine grained sandstones and massive very fine grained sandstone lithofacies with average porosity (18-32%), permeability (400-1189 mD) at depths between 859 and 2129m. The Green cluster is dominated by massive fine grained and massive medium grained sandstone lithofacies exhibit average porosity (15-30%), permeability (110-840 mD) at depth from 880-1805m, while Brown cluster comprises of massive medium grained and massive fine grained sandstone lithofacies exhibit an average porosity (18-25%) and permeability (210-657 mD). The understandings of porosity-permeability continuity can facilitate effective areal sweep efficiency from injected fluid well to production well during recovery. Thus, this approach is important to improve the field plan for reservoir engineers.

Sedimentary Rock Fabric Characterization

“…The fractured-dominated domain is visible in sandstone lithofacie associated with the occurrence of matrix-fracture porosity [23,24] during rapid sedimentation [25] probably occurring during a regime of an abnormally high pore-pressure that exceeded hydrostatic pressure at a given depth [26] in the delta. Other textural characteristics (Table 1) contribute to development variable occurrence and distribution of porosity within the domain.…”