Browsing by Author "Akram, Jubran"

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    Downhole microseismic monitoring: processing, algorithms and error analysis
    (2014-04-09) Akram, Jubran; Eaton, David
    Basic microseismic data processing for hypocentre location estimates is a pre-requisite to extracting information about the stimulated reservoir volume as well as understanding the geomechanics of the fracturing process. The primary objective of this thesis is to investigate the basic processing of microseismic data acquired with receivers in a single observation well, with emphasis on the evaluation and parameter selection of processing algorithms and the associated hypocentre location error analysis. This thesis is made up of five independent studies. The first study discusses the development of a MATLAB based microseismic data processing package (Calgary microseismic processing system; CaMPS). This software is used to process the microseismic data from a hydraulic fracture treatment in western Canada. For reference, the results are compared with those obtained independently by a microseismic services company. The second study examines several single-trace event-detection and arrival-time picking algorithms for microseismic data. A dynamic threshold criterion for event detection and a hybrid, arrival-time picking approach are proposed. The performance of these algorithms is evaluated using synthetic and real microseismic data. The third study describes an iterative cross-correlation based workflow to refine the initial arrival-time picks. This workflow is compared with other single-trace and multi-trace techniques. The proposed workflow provides an arrival-time accuracy of ±0.5 − 1ms for both synthetic and real microseismic data examples considered in this study. The fourth study examines hypocentre location uncertainty and errors due to inaccurate velocity model. The Monte Carlo uncertainty analysis suggests that the velocity errors have a greater impact on hypocentre locations than arrival-time pick errors. The hypocentre location errors resulting from the model calibration process are also discussed, in particular the use of single vs. multiple calibration shots, a priori information, and first vs. direct arrival times. The fifth study discusses the remaining hypocentre location errors after anisotropic model calibration. The behaviour of hypocentre location is discussed when a 1-D layered, isotropic and homogeneous model is used to locate hypocentres from anisotropic and heterogeneous subsurface. The results emphasize the use of a detailed model with anisotropy and lithological or structural variations for improving hypocentre location accuracy.
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    Rational Rock Physics for Improved Velocity Prediction and Reservoir Properties Estimation for Granite Wash (Tight Sands) in Anadarko Basin, Texas
    (2014-08-26) Durrani, Muhammad Z. A.; Willson, Keith; Chen, Jingyi; Tapp, Bryan; Akram, Jubran
    Due to the complex nature, deriving elastic properties from seismic data for the prolific Granite Wash reservoir (Pennsylvanian age) in the western Anadarko Basin Wheeler County (Texas) is quite a challenge. In this paper, we used rock physics tool to describe the diagenesis and accurate estimation of seismic velocities of P and S waves in Granite Wash reservoir. Hertz-Mindlin and Cementation (Dvorkin’s) theories are applied to analyze the nature of the reservoir rocks (uncemented and cemented). In the implementation of rock physics diagnostics, three classical rock physics (empirical relations, Kuster-Toksöz, and Berryman) models are comparatively analyzed for velocity prediction taking into account the pore shape geometry. An empirical (-) relationship is also generated calibrated with core data for shear wave velocity prediction. Finally, we discussed the advantages of each rock physics model in detail. In addition, cross-plots of unconventional attributes help us in the clear separation of anomalous zone and lithologic properties of sand and shale facies over conventional attributes.