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

Reservoir properties and facies characterization from core data and well logging: autochthonous Miocene sediments in the Carpathian Foredeep case study

Laboratory results of total porosity and physical permeability were the basis to calculate Flow Zone Indicator and GR log and porosity log were used for facies identification in the Miocene sandy-shaly sediments in two wells in the Eastern Part of Polish Carpathian Foredeep. There was observed FZI increase with the total porosity from the comprehensive interpretation of logs in the regressive set of parasequences what can be interpreted as better reservoir and hydraulic abilities of them in comparison to transgressive ones. Combining laboratory origin information with well logging results on the basis of facies and FZI correlation worked also as a kind of data scaling

Determination of reservoir properties through the use of computed X-ray microtomography – eolian sandstone examples

A possibility of examination of the rock pore structure by means of the X-ray computed microtomography was presented. Parameters characterizing the pore structure, i.e. porosity and coefficient of homogeneity of pore structure by local porosity examination and box counting dimension and mean chord length and normalized Euler number and coordination number were determined through pore structure image analyses. Complementary methods as pycnometry, mercury injection porosimetry and NMR were used to determine porosity and other factors to make the comparison and determine mutual relationships between petrophysical properties obtained from various sources.The study covered Rotliegend sandstones of eolian origin. Reservoir properties laboratory investigations were focused in three areas located in the marginal part of the eastern erg and middle part of the Polish Lowland Permian Basin. Rotliegend sediments in the study showed changeability in petrography and reservoir properties so the data were grouped into three parts according to geological regions. Computed X-ray microtomography gave differentiation of the investigated areas with respect to their pore structure and porosity development. This differentiation was confirmed by means of other applied laboratory methods

Velocity models for seismics based on well log data

Compressional (Vp) and shear (Vs) elastic waves velocities were determined from logging measurements using FWS tool and acoustic full wavetrains processing using FalaFWS application in GeoWin system. Estymacja program was used to calculate both types of wave velocities (Vp, Vs) and bulk density theoretical formulas, which combine quantities dependent on mineral composition, porosity, water saturation and type of medium in the rock. The results were compared with respect to P and S waves slowless, bulk density and dynamic elastic moduli: Young modulus, bulk modulus, shear modulus and Poisson ratio. It was determined that in the absence of Vp and Vs with a lack of acoustic full wavetrains registration, only the Estymacja program provides the expected results. The FalaFWS application broadens the range of results compared to logging results in depth sections where velocity of mud is higher than the velocity of S wave in formation

Results of the comprehensive interpretation of well logs in carbonate and siliciclastic rocks – similarities and differences in the case studies of selected formations

This paper was made using geological and well logging data from the Cuban oilfield area and the Polish Carpathian Foredeep gas deposit to compare the interpretation process and underline similarities and differences between data analysis from two reservoir rocks of different lithology. Data from conventional hydrocarbon deposits, i.e. the Mesozoic Cuban carbonate formation and Miocene shaly-sandy sediments were processed and interpreted using Techlog (Schlumberger Co.) software. Selected approaches were used to determine the step by step volume of shale, total and effective porosity, water/hydrocarbon saturation (Quanti) and for the comprehensive interpretation of well logs (Quanti Elan). Brief characteristics of the carbonate and siliciclastic formations were presented to indicate that the interpretation methodology oriented to the determination of petrophysical properties depends strongly on the type of reservoir. Cross-plots were presented for primary mineral composition recognition, determination of m exponent and resistivity of formation water in the Archie equation. Effective intervals for the carbonate reservoir were calculated according to the Cumulative Hydrocarbon Column methodology. Finally, the results of the interpretation of well logs were presented as continuous curves of mineral composition, including shaliness, porosity and hydrocarbon saturation. The conclusions included recommendations for the effective comprehensive interpretation of well logs in the carbonate and siliciclastic reservoirs

Department of Geophysics

Department of Geophysics is one of 8 independent units at the Faculty of Geology Geophysics and Environmental Protection

Scaling of well log data for velocity models in seismics

The results from the mathematical operations of filtration and interpolation are presented for dynamic elastic parameters such as P-wave slowness and S-wave slowness, Young modulus and Poisson ratio. The parameters were obtained by interpreting acoustic full waveforms using FalaFWS application of GeoWin system and based on calculations using the Estymacja program. The subject of the analysis were the results obtained from various lithostratigraphic formations in several Polish Lowland's borehole profiles sampled from surface to a depth of more than 5 km. The goal was to scale well log data of a high vertical resolution for seismic purposes. Average values of the elastic parameters were presented for units derived out of geological interpretation. The analysis also included calculation of the Q parameter, which is a measure of energy dispertion of elastic waves in a rock formation

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

Modele prędkościowe na potrzeby sejsmiki na podstawie profilowań geofizyki otworowej Velocity models for seismics based on well log data /

Tyt. z nagłówka.Bibliogr. s. 472.Prędkości fal sprężystych, podłużnych Vp i poprzecznych Vs wyznaczono na podstawie pomiaru sondą FWS oraz w wyniku przetwarzania akustycznych obrazów falowych w aplikacji FalaFWS w systemie GeoWin. Do obliczenia prędkości obu typów fal oraz gęstości objętościowej użyto także teoretycznych wzorów łączących wielkości zależne od składu mineralnego, porowatości, współczynnika nasycenia wodą i rodzaju medium w porach skalnych w programie Estymacja. Porównano uzyskane wyniki w zakresie czasów interwałowych fal P i S, gęstości objętościowej i dynamicznych modułów sprężystości - Younga, ściśliwości objętości i postaci oraz stałej Poissona. Stwierdzono, że gdy nie ma wyników pomiaru w postaci Vp i Vs oraz nie ma zarejestrowanych akustycznych obrazów falowych, program Estymacja jako jedyny daje oczekiwane wyniki. Aplikacja FalaFWS poszerza zakres dostępnych wyników w strefach o niskich prędkościach fali S w stosunku do wyników bezpośredniego pomiaru.Compressional (Vp) and shear (Vs) elastic waves velocities were determined from logging measurements using FWS tool and acoustic full wavetrains processing using FalaFWS application in GeoWin system. Estymacja program was used to calculate both types of wave velocities (Vp, Vs) and bulk density theoretical formulas, which combine quantities dependent on mineral composition, porosity, water saturation and type of medium in the rock. The results were compared with respect to P and S waves slowless, bulk density and dynamic elastic moduli: Young modulus, bulk modulus, shear modulus and Poisson ratio. It was determined that in the absence of Vp and Vs with a lack of acoustic full wavetrains registration, only the Estymacja program provides the expected results. The FalaFWS application broadens the range of results compared to logging results in depth sections where velocity of mud is higher than the velocity of S wave in formation.Dostępny również w formie drukowanej.SŁOWA KLUCZOWE: profilowanie akustyczne, prędkość fal sprężystych podłużnych i poprzecznych, profilowanie FWS, program estymacja, aplikacja FalaFWS, Niż Polski. KEYWORDS: sonic logging, velocity of elastic waves, longitudinal wave, shear wave, FWS logging, Estymacja software, FalaFWS application, Polish Lowland