Integrated Seismic Characterization and Reservoir Modeling of Neocomian Fluvial System for Water Injection: Tengiz Oil Field, Republic of Kazakhstan

Newly processed, high resolution PSDM 3D seismic data have provided important insights into the architecture of a Neocomian fluvial complex located above the super-giant Tengiz oil field in the Republic of Kazakhstan. Produced water from the Tengiz oil processing plant is being injected into Neocomian sandstone interval above the Tengiz carbonate platform. A thorough analysis of new PSDM images has significantly improved the characterization of this shallow, high-sinuosity channel system. This analysis has also enabled the construction of improved numerical models to understand water movements.

A detailed seismic interpretation and reservoir characterization project was completed using several new techniques. Discrete sand bodies were mapped using geobody detection methods on a series of stratal slices to reconstruct the original depositional geometry. Stratal slices were useful to map individual channels and reveal their internal morphology. Multi-attribute cubes and animation provided new insights into the architecture of the channel system.

The interpreted Neocomian fluvial system is characterized by moderate to high-sinuosity channels that range from 40-2000m wide. The internal architecture within the channel belts contains lineaments within point bar deposits, which are interpreted as scroll bars. The high level of stratigraphic detail gained from seismic interpretation was captured in a numerical model of the field.

The interpretation of seismic facies enabled the definition of high Net to Gross (NTG) regions within the channel complex and reduced uncertainty associated with sand distribution. Based on the seismic stratigraphic and seismic geomorphologic analyses, a set of 3D water injection models have been constructed to characterize the range of Neocomian sand connectivity. In order to assess alternate model building strategies and the value of soft constraints such as NTG maps, seismic trends and vertical proportion trends of sand facies, a blind cross-validation was carried out on alternative models. Blind cross-validation was also a useful tool to optimize parameters for property distribution in the model. As a result of this exercise, a suite of low/mid/high case models of sand connectivity were constructed for the Neocomian sand interval. These models have subsequently been used for flow simulation to understand the movement of water in the Neocomian channel system, and to assess the interval connectivity of the water injection sands.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California