Print this pageAAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain
Chemostratigraphic Differentiation between Fluvial and Shore-Face Sands as a Real-Time Geosteering Tool in the Albian Upper Burgan Formation, Minagish Field, West Kuwait
(1) KOC, Ahmadi, Kuwait.
(2) sperry sun Ahmadi, Ahmadi, Kuwait.
The Albian Upper Burgan Formation of Minagish Oilfield consists of siliciclastic sediments, which were deposited in fluvial and tide influenced deltaic to shore-face environments. The uppermost unit of the Formation (U1) is characterised by bioturbated, glauconitic shore-face sands, which are mostly argillaceous and of poorer reservoir quality. The sands (U2 to U4), consist of:
- Channel fill sand-bodies with good to excellent reservoir qualities.
- Sandbar complexes with fair to good reservoir qualities.
Both of the latter facies are influenced by tidal processes that reworked the sediments at time of deposition. This complexity of the channel geometry makes targeting and the drilling of the best reservoir facies a serious challenge. Using elemental Chemostratigraphy that uses whole-rock inorganic geochemistry to characterise and differentiate sedimentary units. This team manage to identify “geochemical proxies” that distinguish fluvial from tidal shore-face sands of the Burgan reservoir. Furthermore, the geochemical proxies also differentiated the apparently monotonous sandstone packages into distinct sub-units that are linked to the underlying mineralogy, e.g. Glauconite and Dolomite, as described in petrographic studies.
Chemostratigraphy has advanced into a proven real-time application that can be utilised:
- For improved borehole positioning while drilling.
- Geochemical data produced from near real-time analyses of cuttings samples (LIBS and ED-XRF) are successfully used for monitoring and optimizing the wellbore in highly deviated wells through Wara and Burgan reservoirs drilled in the Field.
- Applied in slim-hole wells, for which no ‘gamma ray at bit’ or ‘resistivity at bit’ tools are available.
In a recent 4¾" borehole, chemostratigraphic data were used for geosteering and correcting the well path within the Upper Burgan unit U3.