The measurement and interpretation methodology of resistivity logs affected by the Groningen effect – a Polish case study

True formation resistivity Rt measurement is one of the fundamental logs in the calculation of hydrocarbon resources. That is why it is very important to have the most reliable resistivity data possible. In this paper, the various outcomes obtained by Polish well log analysts and engineers for the proper determination of hydrocarbon saturation in the Main Dolomite deposits in the Polish Lowland are presented. The long history of efforts directed to make proper exploitation decisions in wells where the Groningen effect has been observed is illustrated, starting with the standard measurement and interpretational approach, through the modified construction of a reference electrode in a Laterolog device and ending with an examination of HRLA (High-Resolution Laterolog Array) or Array Compensated Resistivity Tool) ACRt results. The processing of resistivity logs with the special Poprawki software is included

Shale Gas in Poland

An example of interpretation of the Silurian and Ordovician shale formations in the Baltic Basin in Poland regarding determination of potential sweet spots is presented. Short geological information shows the position of shale gas play. Description of the data—laboratory measurement outcomes (petrophysical and geochemical) and well logging—presents results available for analyses. Detailed elemental analyses and various statistical classifications show the differentiation between sweet spots and adjacent formations. Elastic property modelling based on the known theoretical models and results of comprehensive interpretation of well logs is a good tool to complete information, especially in old wells. Acoustic emission investigations show additional characteristic features of shale gas rock and reveal that acoustic emission and volumetric strain of a shale sample induced by the sorption processes are lower for shale than for coals

In te gra tion of core, well log ging and 2D seis mic data to im prove a res er voir rock model: a case study of gas ac cu mu la tion in the NE Pol ish Carpathian Foredeep

Geo log i cal mod els play a cru cial role in the de scrip tion and sim u la tion of fluid flow of both hy dro car bon-and wa ter-bear ing strata. Meth od ol ogy, based on the hy drau lic flow unit build on the ba sis of core plug data com bined with rock types de termined from logs and 3D seis mic cubes gen er ated on the ba sis of 2D seis mic sec tions is pre sented. It works as a pos si ble explo ra tion tool for the Mio cene gas ac cu mu la tions in the Carpathian Foredeep of Po land. De ter min is tic and sto chas tic, geostatistical meth ods were used to con struct a static res er voir model from 2D seis mic sec tions, lithological data and hydrau lic flow unit data. A pseudo-3D seis mic vol ume was gen er ated from all of the 2D seis mic data avail able, in or der to aid the mod el ling of hy drau lic flow units. This ap proach is ap pli ca ble to other res er voirs, where the avail abil ity of seis mic data is lim ited. This study dem on strates that even with out 3D seis mic data and with lim ited well log data, the pro posed hy drau lic flow unit ap proach can be suc cess fully ap plied to res er voir mod el ling through the in te gra tion of di verse data sets for a wide range of scales. Key words: hy drau lic flow units, res er voir static mod el ling, po ros ity, per me abil ity, well log ging, 2D seismics

Diverse Scale Data for Shale Gas Formation Description—Why Is Digital Shale Rock Model Construction Difficult? The Polish Silurian and Ordovician Rocks Case Study

The aim of the study was to show that the petrophysical parameters, characterizing the shale gas formation, obtained from the various scale well logging and laboratory methods, correlated among themselves. Relationships determined on the basis of mesoscale (logs) and microscale outcomes (laboratory experiments on plugs or crumbs) were also recognizable in nanoscale in the computed tomography results. Selected logs (spectral gamma ray, resistivity, density, neutron, geochemical and acoustic logs) and laboratory methods turned out to be effective in rock typing and description of petrophysical parameters. Nanoscale results processing and interpretation was supported by the sophisticated special software poROSE (version 3.18, AGH University of Science and Technology, Kraków, Poland) to determine special parameters, which correlated with the standard laboratory outcomes. Results of the mercury injection porosimetry, together with adsorption/desorption of nitrogen at 77 K and pressure decay permeability, were used as the basal parameters for building a digital model of shale rock and a detailed description of the Silurian and Ordovician shale formation, treated as the hydrocarbon prospective unconventional reservoirs. Including the computed X-ray tomography results in the correlation analyses, gave the platform to extend the standard 2D approach in building the rock model to novel, 3D and more detailed presentations of rock characteristics

Geothermal Resources Recognition and Characterization on the Basis of Well Logging and Petrophysical Laboratory Data, Polish Case Studies

Examples from the Polish clastic and carbonate reservoirs from the Central Polish Anticlinorium, Carpathians and Carpathian Foredeep are presented to illustrate possibilities of using well logging to geothermal resources recognition and characterization. Firstly, there was presented a short description of selected well logs and methodology of determination of petrophysical parameters useful in geothermal investigations: porosity, permeability, fracturing, mineral composition, elasticity of orogeny and mineralization of formation water from well logs. Special attention was allotted to spectral gamma-ray and temperature logs to show their usefulness to radiogenic heat calculation and heat flux modelling. Electric imaging and advanced acoustic logs provided with continuous information on natural and induced fracturing of formation and improved lithology recognition. Wireline and production logging were discussed to present the wealth of methods that could be used. A separate matter was thermal conductivity provided from the laboratory experiments or calculated from the results of the comprehensive interpretation of well logs, i.e., volume or mass of minerals composing the rocks. It was proven that, in geothermal investigations and hydrocarbon prospection, the same petrophysical parameters are considered, and well-logging acquisition equipment and advanced methods of processing and interpretation, developed and improved for almost one hundred years, can be successfully used in the detection and characterization of the potential geothermal reservoirs. It was shown that the newest (current investment)—as well as the old type (archive)—logs provide useful information

Geothermal Resources Recognition and Characterization on the Basis of Well Logging and Petrophysical Laboratory Data, Polish Case Studies

Examples from the Polish clastic and carbonate reservoirs from the Central Polish Anticlinorium, Carpathians and Carpathian Foredeep are presented to illustrate possibilities of using well logging to geothermal resources recognition and characterization. Firstly, there was presented a short description of selected well logs and methodology of determination of petrophysical parameters useful in geothermal investigations: porosity, permeability, fracturing, mineral composition, elasticity of orogeny and mineralization of formation water from well logs. Special attention was allotted to spectral gamma-ray and temperature logs to show their usefulness to radiogenic heat calculation and heat flux modelling. Electric imaging and advanced acoustic logs provided with continuous information on natural and induced fracturing of formation and improved lithology recognition. Wireline and production logging were discussed to present the wealth of methods that could be used. A separate matter was thermal conductivity provided from the laboratory experiments or calculated from the results of the comprehensive interpretation of well logs, i.e., volume or mass of minerals composing the rocks. It was proven that, in geothermal investigations and hydrocarbon prospection, the same petrophysical parameters are considered, and well-logging acquisition equipment and advanced methods of processing and interpretation, developed and improved for almost one hundred years, can be successfully used in the detection and characterization of the potential geothermal reservoirs. It was shown that the newest (current investment)—as well as the old type (archive)—logs provide useful information

Multiple Regression and Modified Faust Equation on Well Logging Data in Application to Seismic Procedures: Polish Outer Carpathians Case Study

An appropriate velocity model from well logs is a key issue in the processing and interpretation of seismic data. In a deep borehole located in the central part of the Polish Outer Carpathians, the sonic measurements were inadequate for seismic purposes due to the poor quality of data and gaps in the logging. Multiple regression (MR) and a modified Faust equation were proposed to model the velocity log. MR estimated the P-wave slowness as a dependent variable on the basis of sets of various logs as independent variables. The solutions were verified by the interval velocity from Check Shots (CS) and by the convergence of synthetic seismograms and the real seismic traces. MR proved to be an effective method when a set of other logs was available. The modified Faust method allowed computation of P-wave velocity based on the shallow resistivity logs, depth, and compaction factor. Faust coefficients were determined according to the lithology and stratigraphy divisions and were calibrated with the use of the velocity previously determined in the MR analysis. The modified Faust equation may be applied in nearby old wells with limited logging data, particularly with no sonic logs, where MR could not be successfully applied