Abstract
<jats:p>The paper presents a comprehensive approach to integrating information on carbonate rock formations. An algorithm has been proposed for combining geophysical, geological, drilling, and production data, along with laboratory test results. This integration aims to provide a complete and coherent characterization of the carbonate rock medium. Carbonates, as sedimentary rocks of biogenic, detrital or chemical origin, are characterized by a relatively simple mineral composition (they are composed mainly of calcite and dolomite), while the heterogeneity of the pore space and texture of these rocks is high, which greatly complicates its description. For this reason, three scales of description were defined: macro, meso and micro, and a measurement and interpretation procedure was developed, combining the use of information from all defined scales of rock description for selected petrophysical parameters. Two parameters were considered: a qualitative description of depositional facies/structures (in Dunham’s classification: mudstone, wackstone, packstone, grainstone and boundstone) and a quantitative parameter – fracturing, understood as the total volume of fractures in the rock. The monograph is methodological in nature, i.e. it contains the necessary information on selected carbonate formations treated as examples, and methods of obtaining data from these rocks in order to develop an integration methodology. It consists of chapters presenting the geological characteristics of the research area, the measurement tools used, the collected research material, the components of the proposed integration methodology, and conclusions and discussion of results. This paper presents the synthetic characteristics of carbonate rocks, highlights the importance of carbonates as hydrocarbon reservoirs within Poland’s oil provinces, and provides numerical data from the 2022 Mineral Resource Balance on current production and reserves in deposits where carbonates serve as the reservoir rock. The geological characteristics of the main stratigraphic levels were described based on well profiles developed using data from the northern margin of the Wielkopolska Platform. These were the G-10, G-12K wells and the P-1 well located south of them. A separate object, located north of the above-mentioned ones, was the S-1 well, located in the Wysoka Kamieńska region. In the above-mentioned wells, the object of interest in the subsequent stages of the work were the formations of the Main Dolomite, Ca2, which is a part of Stassfurt cyclothem. Another area from which the data developed in the monograph was obtained is the Paproć region. The analyses were performed on data from the Basal Limestone / Zechstein Limestone, Ca1, of the Werra cyclothem in wells P-19, P-21, P-26, P-27 and P-29. Separately, very briefly, the technical conditions for performing laboratory measurements, the results of which were used in the work, i.e. mercury porosimetry, MICP and helium, nuclear magnetic resonance, NMR and X-ray diffraction, XRD, are presented. The monograph shows examples of using the results of these studies in the interpretation of well logging data. A brief description of well logs was also presented, divided into measurements of drilling electrometry, radiometry, acoustic measurements, dip of layers and methods of electrical, XRMITM and acoustic, CASTTM imaging of borehole walls. Using data from the Basal Limestome / Zechstein Limestone Ca1, and the Main Dolomite Ca2, in the considered boreholes as an example, the methods of interpretation of well logs were characterized, in particular the so-called method of successive exclusions used in the case of a limited number of logs. The results of quantitative interpretation in the form of petrophysical parameters - porosity, PHI, water saturation, Sw, permeability, K and saturation with irreducible water, Swi were used in the integration analyses. The next chapter describes statistical methods used during prediction of the distribution of classes/facies/depositional structures on selected examples. Based on the classification supervised methods, i.e. classification trees and artificial neural networks, an algorithm (computational experiment) for using these methods in the analysis of drilling geophysics data is shown. Elements of the Statistica v.13 software used during statistical analyses are also described. A separate chapter is devoted to the methods of analyzing the fracture ability of the rock medium, both in the form of the qualitative method of Comprehensive Fracture Analysis, KAS, and the quantitative analysis of porosity and permeability of fractures on the micro (microfractures), meso (mesofractures) and macro (macrofractures) scale. Based on laboratory data and measurements with the XRMITM probe for electrical imaging of the borehole wall, the distribution of porosity of individual fracture types in the selected profile was obtained. Details of the organization and operation of the ProGeo v. 6.5 program option, Fracture Tool, which was used during the work were also described. The monography was concluded by outlining a dedicated procedure for the analysis of carbonate formations, whose individual components were validated using sample data. An algorithm was proposed that enables the practical integration of all available data – accounting for differences in measurement scale and accuracy – for constructing a model of petrophysical parameters of carbonate rock formations. The presented examples from boreholes drilling through formations of the Basal Limestone – Ca1, and the Main Dolomite – Ca2 in the Polish Lowlands confirmed the possibility of effective procedure. A method for combining information of different scales and from different sources was shown to enrich the description of carbonate formations. The implementation of elements of the proposed interpretation procedure in industrial projects conducted by INiG-PIB confirmed the effectiveness of the approach. The IT tools used in the analytical work, in the form of Statistica v. 13 software and ProGeo v. 6.5 program, enabled effective calculations and presentation of results, confirming their usefulness in this type of analyses.</jats:p>