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AAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain

From Outcrops to Reservoir, a Comprehensive Approach to Reservoir Characterization

Ailin Jia1; Dongbo He1; Chengye Jia1; Dewei Meng1

(1) Research Institute of Petroleum Exploration and Development, Petrochina, Beijing, China.

General characteristics of Low Permian clastic reservoirs in Ordos basin Northwest China have been reviewed by former researchers. The Shihezi Group sandstones normally have quartz content between 80%-90%, up to 8%-12% lithic, While Shanxi Group have quartz content between 65%-90%, relatively high lithic (He et al. 2003). Petrophysical properties such as permeability and porosity have been investigated (Nan et al. 2005). The Shihezi Group sandstones have mean permeability of 9.1% and mean porosity of 0.98mD. The Shanxi Group sandstones have mean permeability of 6.55% and mean porosity of 10.22mD. Diagenesis phases including compaction, siliceous cementation and genesis of net pay have been argued and compaction is concluded as the main cause of low permeability (He et al. 2004, Nan et al. 2005). While studies concentrated on reservoir equivalent outcrops and the fluvial sedimentary system especially in aspect of channel geometry have not proposed yet.

This paper proposes a comprehensive research compromising outcrop study with available well data (sand thickness variation, stacking pattern, fluid identification, petrophysical property) derived from well logging and core analysis, which provide thorough and detailed information for reservoir characterization.

Reservoir equivalent lower Permian Shanxi (P1s) and Shihezi (P1x) outcrop exposures in the SE and NW of the Ordos basin, Northwest China have been studied. Qualitative data such as bedform geometry, bedset thickness, lateral continuity and net to gross are used to guide the reservoir characterization for braided & meandering channel sedimentology. Field surveys provide direct information which help to micro-facies diagnose and field measurements including width, thickness provide detailed data to channels geometry. Eletrofacies zonation through well logging extrapolation helps to diagnose plain distribution of multi-storey channels and single-storey channels. Thus, conceptual and detailed fluvial depositional models are established.