Laboratory measurements and well logging for digital rocks models of Palaeozoic tight sedimentary rocks from Poland

Abstract

Well logging (measurement and interpretation) is usually successfully used for quantitative and qualitative analysis of water and hydrocarbon reservoirs to determine saturation and other petrophysical properties. In combination with the results of laboratory measurements on core samples it provides reliable, unique and improved continuous information on rock parameters in whole wells. Digital rock models of Palaeozoic sedimentary, low-porosity and low-permeability tight clastic rocks were constructed on the basis of laboratory data. Cluster analysis in classic algorithm version with k-mean method was used. For digital rock models construction several parameters were included, i.e. bulk density, pycknometer total porosity, total porosity from micro-CT, absolute permeability, P- and S-wave velocity ratio, effective porosity, Swanson parameter from mercury injection porosimetry, shaliness, clay-bound water, capillary water and moveable water from NMR, and uniaxial compressive strength. Three models corresponding to selected groups of rocks were created on the basis of 28 samples.

There were models of good, transitional and bad quality elastic and reservoir rock properties. Each model was characterized by various physical parameters. The most important was the model of good quality reservoir rock comprising samples of high porosity and relatively high permeability being potentially tight reservoir rocks.

Rock classification done on the basis of laboratory data was applied to well log data regarding the division of geological profiles into intervals with the properties similar to those characterizing the laboratory data models (Fig. 1). However, when laboratory measurements differed significantly from the results of well log data, in some wells it was impossible to distinguish intervals with parameters set by the rock models.

The presented solution is similar to HRA analysis (Heterogeneity Rock Analysis) based on the criteria parameters defined from well logs interpretation and used in commercial software (for instance by Schlumberger Techlog). It enables limitation of coring only to the intervals offering expected petrophysical parameters.

The presented method can be also applied as a scaling procedure of laboratory results and well logging data. Transferring information from the micro (or nano) scale representing results of laboratory measurements, to the mezzo scale (well logs), and also macro scale (seismics) is an important issue in detailed analysis of reservoir rocks in case of global approach of sedimentary basin analysis. This study was financed in project No. DEC-2011/03/N/ST10/05354 by National Science Centre. (To view figures go to Search and Discovery)

AAPG Datapages/Search and Discovery Article #90226 © 2015 European Regional Conference and Exhibition, Lisbon, Portugal, May 18-19, 2015