It is a considerable challenge to effectively develop hetero-geneous fractured reservoirs in complex structural settings. Here we present a case study of a fractured basement reservoir hosted in structural highs formed by fault-controlled blocks in a rift setting. A wide range of data were available to study the current reservoir. The seismic database includes a wide-azimuth data set, as well as an extensive set of derived attributes and structural interpretation. Azimuthal anisotropy, automatic fault detection, and rms amplitude proved to be most useful in the description of the fracture network, the fracture corridors, and a thin, permeable sandstone layer above the basement, respectively. An additional advantage of the wide-azimuth survey was that it provided an optimum illumination in complex structural settings such as the current case. To complete this large-scale data set, conventional log suites and image logs were acquired in most of the wells. Borehole image-log studies were conducted to interpret and recognize fracture features. Regarding dynamic information, flowmeter logs were acquired in addition to the production history. The main objectives of this integrated study were the creation of a conceptual model for well planning and to constrain the static and dynamic properties of the reservoir model.

This paper presents the workflow and the results of integration of seismic, well and production data on Habban Field to optimize well locations. Habban Field is located in the Jurassic Marib-Al Jawf-Shabwah basin of Yemen (Block S2). Development targets in Habban Field are fractured Precambrian Basement, Kohlan and Shuqra formations (Middle Jurassic). Main challenges faced in the Field are Basement heterogeneity, fracture distribution and their connectivity, lateral variation of Kohlan Formation and the overlying salt diapirs/walls hampering the seismic imaging. The difference between a good and a dry well is whether it is encountering main fracture corridors or not. Fracture corridors (along the faults) have limited lateral extent and due to overlying salt diapirs well trajectory optimization is very challenging. Reflection pattern in the Basement is quite chaotic. Therefore, it was important to come up with a workflow to image faults within the Basement so that highly deviated to horizontal wells can be drilled to enhance production and optimize recovery. In order to address these challenges, wide azimuth 3D seismic was acquired and processed in different azimuths. The study has been conducted using 3D seismic dataset and derived seismic attributes combined with information from thirty one wells including image and production log interpretation. The workflow highlighted the value of G&G integration to better outline uncertainty and to mitigate risks during well locations and trajectory planning. In this contest structural attributes (i.e. AntTracking) have been crucial in order to define and identify the faults zones for optimizing horizontal wells targeting multiple fracture zones. On the other hand integration of G&G and production data highlights the limitation in defining a one-to-one correlation between seismic, well and production information mainly due to reservoir complexity and scale resolution.