The prediction of porosity in the Permian (Zechstein 2) carbonate of eastern Netherlands using seismic data

Abstract

The depositional model of the Zechstein 2 carbonate section is of such a complex nature that it is not possible to predict high-porosity zones solely from geologic data. We describe a two-phase study into determination and prediction of porosities in the Zechstein 2 carbonate in the eastern Netherlands.Phase 1 was the basic feasibility study and consisted of two parts, namely, a model study followed by a well-log study. In both parts, acoustic impedance logs were filtered to test the feasibility of resolving porosity changes within the frequency range of seismic data.Based on our comprehensive model of the environment of deposition of the Zechstein cvaporites, a number of acoustic impedance logs were constructed, each log representing a particular environment. These logs then were filtered with a suite of band-pass filters. It was our observation that the gross changes in porosity were easily recognized.The model study was followed by a study of acoustic impedance logs from actual downhole measurements taken over intervals with depositional environments similar to those represented in the model study. In spite of geologic variations, the changes in porosity were easily observable.Phase 2 involved the prediction and verification of porosity. An exploration well, planned to penetrate the Zechstein 2 carbonate, was connected to a previously drilled carbonate test by a good quality seismic section. In the previous well, porous limestone approximately 60 m in thickness was penetrated. From the combined well and seismic data, we predicted that a similar development of porosity could be expected in the new location. Subsequent drilling proved the presence of porous carbonate approximately 50 m in thickness developed in an environment of deposition similar to that encountered in the other well. This technique has allowed us to predict reservoir porosity and will be used to develop new structural/ stratigraphic prospects.

Late Permian (Zechstein) carbonate-facies maps, the Netherlands

“…Literature shows the importance of 3-D seismics in Zechstein hydrocarbon exploration (Maureau & Van Wijhe, 1979;Karnin et al, 1992;Gorski et al 1999;Peryt & Raczylski, 1999). Only the eastern part of the Z2 Carbonate facies map is based upon 3-D data; the other maps are based upon well-data.…”

Integrated Approach for the Petrophysical Interpretation of Post-and Pre-Stack 3-D Seismic Data, Well-Log Data, Core Data, Geological Information and Reservoir Production Data via Bayesian Stochastic Inversion

“…To the author's knowledge, the first suggestion of the quantitative integration of 3D seismic data and well logs to constrain hydrocarbon reservoir models can be traced back to . Estimation of porosity based on regression formulas between well-log acoustic impedance (or interval transit time) and porosity were reported by Maureau and Van Wijhe (1979). They applied such regression formulas to infer spatial distributions of porosity from seismic-derived acoustic impedances.…”

“…Applications and limitations of seismic-guided hydrocarbon reservoir analysis can be found in the technical literature (Maureau and Van Wijhe, 1979;Doyen, 1988;Kalkomey, 1996;Chawathe et al, 1997;Balch et al, 1999). The quantitative use of seismic amplitude variations in space and seismic time (or depth) offers a powerful tool to guide the simulation of inter-well reservoir properties.…”

Seismically detected porous Zechstein carbonates in Southern Jutland, Denmark

“…Porous Zechstein carbonate deposits of the Southern Zechstein Basin have for many years been the target of intense investigation, which has resulted in commercial hydrocarbon production in Great Britain, the Netherlands, Germany and Poland (Clark 1986;Maureau & van Wijhe 1979;Mathisen & Budny 1990;Antonowicz & Knieszner 1984). The present study focuses on the Danish part of the Southern Zechstein Basin situated in Southern Jutland using a database consisting of 10 wells (excluding the confidential Løgumkloster-2a/b well drilled in 19931.1 km southsouthwest of the Løgumkloster-1 well), and more than 2000 km of 2D seismic data acquired by various contractors (Fig.…”