Facies Analysis in Petroelastic Modeling

Uspenskaya, Ludmila ¹; Kalmykov, Georgy ¹
(1) Moscow State University named after Lomonosov, Moscow, Russian Federation.

This work is devoted to the technique of the integrated log and core data interpretation for development of accurate petroelastic model and proper estimation of compressional and shears waves velocities as well as fluid substitution simulation. Facies analysis and linking facies to rock properties is an important procedure for petroleum geology due to the fact that lithofacies are major control factor of the depositional geometries, sedimentation conditions, lithological and chemical changes and porosity distribution.

A facies is defined as a rock unit with distinctive lithological composition, grain size, bedding characterization. Every facies have appropriate specific petrophysical properties (at first, total porosity and clay volume), that’s why consideration and correct account of lithological composition is necessary for petroelastic modeling.

Special workflow was developed for petroelastic simulation and fluid substitution. We used the Xu and White’s relation for p-wave and s-wave velocities modeling in shaley sandstones. Fluid properties were estimated with Batzle and Wang empirical equations for fluid substitution.

The practical realization of proposed algorithm was carried out for middle givetian stage of devonian system in Caspian region field. Studying geological sequence consists of clastic rocks with complex mineral composition. Current sequence contains of three facies: alluvial, delta plain and submarine delta facies.

Volume of clay and reclaiming cement increases from top to bottom of the formation. Kaolinite clay composition predominates at the top of the geological sequence. Hydromica contain grows up from top to bottom.

Petroelastic modeling was carried out twice. The main result of petroelastic models comparison is a conclusion that an elastic property modeling is more accurate with facies analysis than without it. Petroelastic modeling and fluid substitution outcomes may be used for accurate stratigraphic shift of seismic and log data while development of the low-frequency seismic model. Proposed workflow helps to find the relation between elastic rock properties derived from seismic data and petrophysical properties.

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.