66th EAGE Conference & Exhibition

P314 NEW TRAVELTIME APPROXIMATIONS FOR A TRANSVERSELY ISOTROPIC MEDIUM Abstract The basic idea of this paper is to derive approximate equations for vertical slowness for P- and SVwaves and PP SS and PS traveltimes in TIV media not using a weak-anisotropy approximation. Comparison with the weak anisotropy approximation shows that the first and second terms in Taylor series are the same as were used in weak anisotropy approximation but the third term is non-linear with respect to anisotropy parameters and differs from one in weak anisotropy approximation. This fact results in different definitions of heterogeneity coefficient in the traveltime approximation.

P322 EFFICIENCY OF MAGNETOTELLURIC SOUNDING DATA INTERPRETATION USING EM ENERGY VELOCITY METHOD 1 1D inversion of magnetotelluric sounding data is often employed in initial interpretation of magnetotelluric data for heterogeneous earths (Trapeznikov et al. 1997). The real earth is usually approximated by means of a 2D model. For 2D models the components of the impedance tensor depend not only on the frequency of MT field variations conductivity distribution in the neighbourhood of MT sounding site and the azimuth of the axis of measurement system but also on the type of polarization of the primary MT field as well. The response

P324 MAGNETOTELLURIC SOUNDINGS IN THE NORTH GERMAN BASIN Abstract Introduction The lithofacial character of the Lower Carboniferous in the deep subsurface of the North German Basin is characterized by two different types of facies: the clastic-terrigene Culm of the Variscan synorogene flysch stage developed in the Rhenohercynian trough (basin facies) and the carbonateous-marly-clayey development of Carboniferous limestones forming the carbonate platform of the pre-Variscan foreland (shelf facies). Asymmetric distribution of facies and thicknesses is typical of the Rhenohercynian trough and indicated by increased thicknesses of flysch sequences in its southern part and reduced thicknesses of pelagic stillwater sediments including black

P326 PILOT PROGRAM OF CENTRAL ASIA EM MONITORING SYSTEM Summary 1 The Tien Shan mountains of Kyrgyzstan are an active geodynamic region. In 2003 IVTRAN (International Scientific Station at Bishkek Kyrgyzstan) and Phoenix Geophysics (Toronto Canada) jointly installed near Bishkek a station for monitoring natural and artificial electromagnetic fields using Phoenix magnetotelluric (MT) equipment. Introduction The main goal of the joint project was to install an EM monitoring system (based on Phoenix MTU-D equipment) in the North Tien Shan seismic active zone. The system was installed in an industrialized area of the Bishkek geodynamic Polygon (BGP). Recent reports indicate that

P328 MARINE TRANSIENT ELECTROMAGNETIC FOR HYDROCARBONS SEARCH ON A SHELF Abstract 1 Electric reconnaissance is especially effective in search for the located congestions of deposits of oil and gas on the shelves. Accumulated data analysis has allowed researchers to establish that abnormal geophysical effects on oil and gas fields are caused not only by the influence of a hydrocarbons (HC) deposit but also by changing of mineralization of underground waters and by secondary change of rock surrounding (overlapping) deposit. These factors are the reason for the increase of electric resistivity change of polarizing properties of rock [5]. Marine electric prospecting

P333 Static and Dynamic Young’s Modulus of Marly Chalk from the North Sea Introduction 1 Deformation properties of a rock are governing factors for production of oil from a reservoir. These properties can be either determined from geotechnical consolidation testing (also called static tests) or from acoustic data (dynamic tests). The main differences between the two tests lie in the frequency of the measurements and the strain amplitude used in the tests. When a sound wave propagates through a porous medium the deformation of the grains is elastic. In a geotechnical test the strain is larger and a non-elastic deformation

USE OF COMBINED SEISMIC INVERSION AND HFI DATA TO EVALUATE A CHALK PROSPECT Abstract 1 AUTHORS 1 2 1 E. TORGERSEN J. MOE K. R. VAGLE Address 1 ConocoPhillips Exploration Scandinavia P.O. Box 220 N-4098 Tanager Norway 2 Ødegaard Norge A/S Norway In between two exploration wells a four-way closure was identified partly associated with a seismic amplitude anomaly at the Top Ekofisk Fm. Nearby wells had not penetrated the upper part of the Chalk Group with the same or comparable seismic characteristic. The possibility that the undrilled event was associated with clastic sediments was not neglected. The seismic characteristics

P342 ELASTIC IMPEDANCE REVISITED Introduction 1 Elastic impedance is a relatively simple concept but is somewhat elusive in practice. Just as contrasts in an acoustic impedance profile convolved with a wavelet generate normal incidence seismic data there should be an "elastic impedance" profile whose contrasts would generate wide-angle reflections. The problem is that there is no simple closed form expression for this quantity. There are various ways to approximate it. One is to integrate Aki and Richards' (1980) approximation for the Zoeppritz equation (Connolly 1999 and Sena 1997). The result is useable but unsettling with angle-dependent (or even depth-dependent) fractional

P344 A FIELD EXPERIMENT TO STUDY WAVE PROPAGATION IN GAS-SATURATED AND FRACTURED ROCKS. Abstract 1 Six seismic tomography surveys between four boreholes have been acquired at a hydrogeological test site in the Cretaceous Chalk Yorkshire UK. Data were acquired before and after air injection into a fractured region of the geological sequence. Time-lapse velocity tomograms revealed that the air had migrated rapidly to the top of the sequence. Velocity anomalies of up to 14% were observed. Amplitude differences between the crosshole seismic data before and after air injection were attributed to small traces of air in 45 degree conjugate fractures

P346 ACOUSTIC ANISOTROPY OF MUDERONG SHALE UNDER TECTONIC STRESS AND HIGH PORE PRESSURES Summary 1 A triaxial testing programme was undertaken on core samples of Muderong shale. Muderong Shale is a regional top seal in the Carnarvon Basin on the Northwest Shelf of Australia. The testing programme involved stepwise increases in confining pressure with drained pore pressure conditions. During each confining pressure cycle a differential stress state was progressively applied by means of an increasing axial load under undrained conditions simulating a high horizontal stress field. Stresses and pore pressures were increased to well into the over-pressured regime. The core