EAGE Conference on Exploring the Synergies between Surface and Borehole Geoscience - Petrophysics meets Geophysics

A-3 IMPROVEMENT OF 4D SEISMIC INTERPRETATIONS BY INTEGRATION OF WELL INFORMATION; EXAMPLES FROM THE GULLFAKS FIELD NORTHERN NORTH SEA 1 OSCAR KELDER PER DIGRANES and LARS-KRISTIAN STRØNEN Statoil 4035 Stavanger Norway Abstract The last few years time lapse seismic has proven to be a powerful reservoir management tool for the Gullfaks oil field in the North Sea. It considerably improves the drainage understanding of the field and has resulted in several potential new infill drilling targets of which one already has successfully been drilled. The validity of several 4D observations is often hampered by interpretational uncertainties due to data quality

A-6 SATURATION ESTIMATION USING BOTH SEISMIC AND WELL DATA Abstract 1 We describe a monitoring methodology which allows the localization of a gas zone within a reservoir the measurement of the gas thickness and an estimation of the gas saturation. The methodology has been tested both on time lapse sonic and seismic data recorded on an underground gas storage facility of Gaz de France. The method is based on the Gassmann model on the measurement of time shifts obtained by cross-correlation techniques and on the computation of a specific seismic function. With time-lapse sonic data it has been possible to

A-9 A NEW SEISMIC LOOK AT RESERVOIR MONITORING JULIEN MEUNIER¹ FRÉDÉRIC HUGUET² and PATRICK MEYNIER³ ¹Compagnie Générale de Géophysique Rue Léon 1 Migaux 91341 Massy France ²Gaz de France ³Institut Français du Pétrole Summary 1 After various attempts at using vertical seismic antennae to obtain enhanced seismic data above the Céré-la-Ronde gas storage reservoir and analysis of these attempts a new monitoring method was developed. It uses low-energy stationary seismic sources operating permanently in conjunction with vertical multi-component receiver antennae. The low spatial density of the data remains consistent with the density of conventional reservoir simulators. Its high temporal density

A-11 USE OF NEURAL NETWORKS IN LOG'S DATA PROCESSING – PREDICTION AND REBUILDING OF LITHOLOGIC FACIES Abstract 1 When a log is missing in a drilling hole geologists hope to deduce it from others logs available in another part of the hole or in a neighbouring hole in order to define the lithologic facies of the hole. This paper presents a neural network method to predict the missing log's measure from the others available log's measures. This method based on Multi-Layer Perceptron (MLP) acts as a non linear regression method for the prediction task and as a probability density distribution

A-16 PERMEABILITY INVERSION AND WATER-CUT FORECASTING USING SATURATION HISTORY FROM TIME-LAPSE SEISMIC AND SEISMIC ATTRIBUTE MAPS Abstract 1 Time lapse seismic is used to monitor the reservoir during production. Assuming seismic repeatability it is possible to couple seismic changes in the reservoir to flow property changes as a result of production. Successive slices give direct information over the speed at which the saturation front propagates through the a-priori unknown permeability field. The propagation speed of the saturation front contains useful information about the fluid flow velocity field in the observed medium. A relation between the velocity map and desired reservoir

A-18 INTEGRATING CORE MEASUREMENTS AND BOREHOLE LOGS WITH SEISMIC DATA IN THE STATFJORD 4D PROJECT ANNE-KARI FURRE and IVAR BREVIK Statoil R&D Postuttak 7005Trondheim Norway Abstract The Statfjord field straddles the border between Norway and UK. A total of 570 Sm 3 of oil has been produced from the field since production start in 1979. As part of an increasing oil ratio (IOR) scheme a seismic reservoir monitoring study was carried out based on totally three seismic surveys; one in 1979 (pre-production) one in 1991/92 and one in 1997. The seismic surveys together with a large amount of well logs

A-20 TIME-LAPSE BOREHOLE SEISMIC STUDY IN VACUUM FIELD NEW MEXICO – VELOCITY AND Q FACTOR CHANGES DUE TO CO2 INJECTION WITHIN A CARBONATE RESERVOIR GWÉNOLA MICHAUD¹² ¹Colorado School of Mines 1500 Illinios Street Golden CO 80401 USA ²Compagnie Generale de Geophysique Abstract 1 The Reservoir Characterization Project of the Colorado School of Mines has recorded two multicomponent borehole seismic surveys at Vacuum Field New Mexico. These two surveys were recorded in December 1997 and 1998 before and after eight months of CO2 injection. Each borehole dataset is composed of a near-offset VSP and a 3D VSP. The purpose of these

A-23 GEOPRESSURE PREDICTION AND ANALYSIS IN DEEPWATER GULF OF MEXICO USING ROCK PHYSICS AND SEISMIC ATTRIBUTES Abstract 1 N.C. DUTTA¹ S. GELINSKY² M. KHAN ¹ Z. ZHENG² ¹Baker Hughes - Western Geophysical PO Box 2469 Houston TX 77252 USA ²Baker Hughes – Baker Atlas Deepwater drilling is risky and expensive. Proper well planning requires reliable estimates of pore fluid pressure prior to drilling. While drilling monitoring and frequently updating these estimates guarantees environmentally safe drilling. Most common practice to predict pore pressure is to use conventional seismic stacking velocities as porosity indicators in conjunction with a Normal Compaction Trend (NCT)

A-25 PETROPHYSICAL MODELING USING SEISMIC ATTRIBUTES AND GEOLOGICAL MAPS Abstract 1 Subsurface models of reservoir properties like porosity or permeability are often related to lithofacies distribution. In addition seismic attributes can also provide valuable information regarding the lateral variation of reservoir properties which well data cannot furnish because of relatively large well spacing. An integrated method is proposed here to generate a reservoir model in terms of physical properties by the control of lithofacies and seismic information. Neural network and geostatistics are incorporated in this method. The method is divided in three steps: 2D neural network prediction of porosity where

1 A-27 A BREAKTHROUGH IN RESERVOIR POROSITY ESTIMATION USING DOMINANT FREQUENCIES EXTRACTED FROM 3-D SEISMIC WAVELETS Abstract Hydrocarbons accumulate in reservoir rock pore spaces which makes porosity estimation one of the major applications in oil and gas industries. Two methods are currently used in the industry to estimate porosity. The first is the well logs-based method that depends mainly on empirical formula used to transfer reservoir rock physical properties into porosity. The second is based on empirical equation which linearly (e.g. regression formula) relates well logs estimated porosity and seismic impedance and then populates the relation between wells. A new