Mosab Nasser

NLTE accretion disc models for the AM Canum Venaticorum systems

We present models of the optical spectra of two types of accretion disc atmospheres: a pure helium model and a H-He model, in a low mass ratio, helium transferring, interacting binary white dwarf system. The computations are restricted to stationary discs in LTE and NLTE cases. We also investigate the influence on the spectra of some of the disc parameters such as the mass accretion rate, the angle of inclination, the H/He mass ratio, and the inner and outer radius of the disc. Departures from LTE are also investigated in order to assess the necessity of computing more complicated and more time consuming models. We found that dierences in predicted equivalent widths of helium line computed in LTE and NLTE models range between 10 and 40 percent. Finally we compare our disc models with 4 of the AM CVn systems observed with the Nordic Optical Telescope: AM CVn, HP Lib, V803 Cen and CR Boo to determine their parameters as mass transfer rates and inclinations of their discs.

Time‐lapse seismic makes a significant business impact at Holstein

acquisition over the Holstein field (undershoot polygon in green). NRMS is estimated in a 1s window centered at 2.5s. An average NRMS value of 0.23 on final migrated data and an average shot+receiver repeat error of 75m is achieved. Time-lapse seismic makes a significant business impact at Holstein Hesham Ebaid*, Mosab Nasser, Paul Hatchell, Shell Exploration and Production Co, Darrell Stanley, BP America Inc.

Rock Physics - Modeling impact of pore fluid, lithology and depth on AVO signatures

Summary Elastic properties of rocks are strongly dependent on local geology and can significantly vary within the same sedimentary basin. Both depositional environment and burial history are two critical factors that control the elastic properties of the subsurface rocks, and knowing the impact of these factors on the seismic response may increase our ability to predict hydrocarbon accumulations. The variation of reflection coefficients with source-to-receiver spacing in multi-offset seismic data, known as AVO, often contains critical information about the lithology and the pore fluid in the subsurface. In this paper, we discuss rock properties analysis of sands and shales in a deep water setting and the use of trend based rock physics modeling approach to model the clean sand, pure shale and shaly sand log response. Moreover, practical aspects of AVO modeling given both, a shalesand interface as well as log data and model response will also be discussed. The expected AVO response as a function of lithofacies, pore fluid, burial depth as well as the AVO approximation used in predicting the AVO response will be the focus of this discussion. Six wells from deep-water Angola are the basis for this work with the goal of assisting exploration activities in the area.

Integrating rock physics and full elastic modeling for reservoir characterization

Rock physics establishes the link between reservoir properties, such as porosity, lithology, fluid type and the seismic response. It is a tool by which a range of subsurface scenarios can be built to estimate the seismic response beyond what is observed at the well location. In this study we show how rock physics and full elastic 2D seismic forward modeling can be integrated to produce realistic subsurface images, which can be used in conjunction with 3D seismic interpretation.

Rock physics analysis of deepwater sediments, West Africa

Summary Well logs from deepwater Angola are texturally interpreted using a combination of petrophysical and rock physics models. The Thomas-Stieber model predicts the porosity resulting from various modes of sand-shale mixing. The Yin-Marion-Dvorkin-Gutierrez model predicts the associated P-wave velocities. Together, they offer a higher degree of constraint of formation properties.

An Integrated Approach for Building Geologic Models Consistent with Seismic Data

We demonstrate how rock physics, when coupled with seismic interpretation, can lead to building geologic models that are consistent with seismic data. This approach was tested on the Bengo discovery, located offshore Angola. Two wells (discovery & appraisal) were used in this study to build a rock physics model which relates the seismic response to rock and fluid properties, which were later used for populating the geologic model. This study encompasses surface and subsurface elements including geology, geophysics, petrophysics, and reservoir engineering. However, in this abstract we will only focus on the geology and geophysics elements, which are critical for this study.

Geophysical Pore Type Characterization from Seismic Data in Carbonate Reservoir

Pore geometry in carbonates control the fluid flow properties and geological story, the purpose of our work is to predict pore type distribution from well observations and seismic data based on geologic understanding of the reservoir. Based on developed rock physics model which can take into account volume fraction of pore type quantitatively, we bridge the three defined geophysical pore type with extracted seismic properties from seismic data. The approach is evaluated on real well log data and seismic data from offshore Brazil carbonate reservoir, we obtain the distribution of reference pores, stiff pores and cracks which can be used to predict reservoir permeability.

4D Seismic Directly Impacts Business Decisions in the Deepwater Gulf of Mexico

In Gulf of Mexico (GOM), loop and eddy currents can cause large 4D shot and receiver location errors between baseline and repeat streamer surveys. These large repeatability errors are seen as a hindrance to the application of 4D seismic technology in the