Bashar Al-Qadeeri

PP Azimuthal-amplitudes And -acoustic Impedance For Fractured Carbonate Reservoir Characterization

Four azimuth-sectored 3D P-P volumes were pre-stack time migrated (PSTM) using the same velocity field. These high-fold full-azimuth full-offset data (4,000-5,000 traces were summed in each bin in each azimuth sector) of high S/N enable azimuthal analysis of amplitudes, and acoustic impedance, at the top of the reservoir unit of interest (14,000 ft depth). Each azimuthal cube was inverted for acoustic impedance after prestack time migration. These high-fold azimuth-sectored PSTM 3D data enable us to determine the azimuthal variation of amplitudes, and acoustic impedance, assuming orthorhombic symmetry (flat layers and one set of vertical aligned frctures), and so map relative fracture density and fracture azimuth of the open fractures that flow hydrocarbons in the reservoir unit. The N-S natural fracture strike seen at Well A in the reservoir unit are parallel to the local max hor stress, as interpreted through borehole breakout and the induced fractures. The N-S trending fractures at Well B cause the fracture-parallel amplitude to be the azimuthal minimum, for the top of this low-impedance reservoir. The acoustic impedance inversions showed max acoustic impedance N-S, parallel the fractures and max hor stress, corroborating the interpretation of the azimuthal amplitudes, and tieing the well data. The spatial heterogeneity of the fractures in the upper part of the reservoir unit is mapped using the azimuthal variation of PP amplitudes, and acoustic impedance, after fitting to the cosine 2theta curve.

Building a Seismic-driven 3D Geomechanical Model In a Deep Carbonate Reservoir

In this paper we show how to extend seismic-driven earth model building into the domain of geomechanics and drilling. A mechanical earth model (MEM) is a quantitative description of rock mechanical properties and in-situ stresses in the subsurface. Formation strength and in-situ stress are key components that impact well design. Most mechanical earth models, even today, are one-dimensional (1D), based on well and drilling data alone. The concept of using seismically derived horizons and velocities to extend the MEM into 3D space was introduced a few years ago. Very recently, a few authors have demonstrated the power of seismic inversion to improve the resolution and quality of a 3D MEM. We present a case-study from Kuwait (Sabriyah field) where a 3D geomechanical model was built using a combination of wellbore geomechanics, geologic structure, and seismic inversion-derived lithofacies and elastic properties. We show critical challenges facing seismic-based geomechanical model-building, demonstrate current solutions, and discuss future strategies.

A Well-driven Interbed Demultiple Workflow for Deep Carbonate Reservoirs of Kuwait

As in almost all Middle East basins, seismic data from North Kuwait very often suffers heavily from contamination by interbed multiples. As a result, both structural and stratigraphic mapping and inversion derived elastic attributes (acoustic impedance) are significantly affected. This is a major problem for one of the deep Carbonate reservoirs, currently the subject of detailed reservoir characterization studies in support of an extensive drilling program. In this paper we describe the successful application of a well-driven interbed demultiple workflow to a 3D point-receiver dataset from Kuwait. The workflow combines pre-imaging components such as Extended Interbed Multiple Prediction (XIMP) with post-imaging components that include well-driven parameter optimization and inversion. We show the improvement both in the seismic image, acoustic impedance, and resulting reservoir properties.

Exploration Strategy For Unconventional Reservoirs In the Lower Cretaceous Section of Kuwait: Case Study

Kuwait Oil Company (KOC) the State oil enterprise of Kuwait holds exclusive rights to Exploration and Production in the State of Kuwait. As part of the strategy to add new reserves to its portfolio, KOC has embarked upon an aggressive exploration campaign of the hitherto less explored stratigraphic levels. The Lower Cretaceous stratigraphic section, a set of fracture associated unconventional reservoirs, is one such play currently under active exploration.