THE 3D GEOMODEL OF FLUVIAL-TIDAL TRANSITION ZONE DEPOSIT: A CASE STUDY OF RESERVOIR D-10 IN NORTH KUTAI LAMA, STRUCTURE, SANGASANGA FIELD, KUTAI BASIN, EAST KALIMANTAN

• Main Author: Rizal, Ferdi
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/74832
• Institution: Institut Teknologi Bandung

Main oil production at the NKL structure comes from reservoir D-10, about 70% of total production which is located on the east flank of northern Anticlinorium Samarinda. However, understanding this reservoir is quite challenging due to the few wells penetrated in the flank area, besides that, this reservoir is not connected to the reservoir at crestal. The compartement issue has recognized due to reservoir at flank is located below the oil-water contact of the reservoir at crestal and observed two different trends of pressure evolution between crestal and flank. The early step to do analysis was defining litho and electro-facies (refers to Walker dan James, 1992 dan Miall, 1977) then continued with well-to-well correlation based on cyclothem concept (Weller, 1931 and McCabe, 1984). In order to understand geometry, dimension and heterogeneity of reservoir D-10 therefore a conclusive of paleo-depositional environment could be achieved by using an integrated approach to utilizing and synthesizing various different types of data, such as biostratigraphy analysis from several fossils, lithofacies, grain size, sedimentary structure, paleocurrent analysis, and salinity distribution of reservoirs. Afterwards creating 2D NTG map, there are two steps i.e. reconstruction of channel polygon and distribution of NTG pattern inside channel polygon. In the 3D of facies modeling, 2D NTG was converted into 3D as shale and channel trend by multiplying 2D NTG map with percentage of sandstone and shale from VPC in each vertical layer. This 3D NTG has been used as a trend of facies with SIS method and as a secondary variable while property modeling with SGS. According to an integrated approach, the D-10 layer has three architectural elements such as mud flat, crevasse splay and fluvial-tidal in transition zone (FTZ) which is composed by several compartements, mostly it was due to stratigraphic trap. The D-10 reservoir is located at flank and crestal identified in the same channel system but different compartement. Another compartement that separates reservoir at the crestal has caused by stratigraphic and fault sealed. The total initial volume of hydrocarbon (IHIP) at flank and crestal based on this 3D reservoir modeling are 7.04 MMstb and 1.23 Bcf with Np 1.41 MMstb (recovert factor, RF 20%) abd 0.18 Bcf (RF 14%). Specifically, IOIP at flank area has 6.76 MMstb (RF 18%) is still realistic after comparing with Np. Analysis of ergodicity was performed as part of uncertainty analysis and sensitivity in order to have statistical initial volume of hydrocarbon. The new 3D reservoir model is expected to help on further of field development to be more accurate on volume calculation, identification of sweet spot area for the new well proposals, water injection strategy for pressure maintenance and reservoir simulations.