Browsing by Author "Harris, Jerry, M"

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    Seismic velocity tomography for CO2 monitor in subsurface geological structures
    (Elsevier, 2018) Raji, Wasiu O; Harris, Jerry, M; Lu, Shaoyu
    The storage of CO2 in depleted hydrocarbon reservoirs and saline water aquifers is a leading solution to Global Warming due to CO2 emission to the atmosphere. The capture of CO2 from major CO2-emitting plants and its storage in underground geological structures has a potential to reduce Global Warming by about 60%. A procedure for monitoring safe and secure storage of CO2 in underground geological structures is demonstrated in this study using seismic velocity tomography. The tomographic method uses first arrival traveltime to estimate velocity of geological structure along the ray path. The inversion procedure utilizes optimized objective function that consists of two parts: (i) a part that minimizes the misfit between the observed and inverted data, and (ii) a part that enforces the true shape and structure of the real geology. First, the method is applied to invert the velocity structure of a west Texas oilfield, and later to reconstruct the velocity structure of Marmousi models before and after CO2 injection. The results of the tests confirm the appropriateness of the procedure for CO2 monitoring. The inverted velocity tomogram for the post-injection stage shows velocity perturbation due to CO2 presence and the progression in CO2 front. Technology for monitoring CO2 in geological storages as demonstrated in this study is crucial to forestall CO2 leakages and its negative consequences on the environment.
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    Wavefield Analysis of Crosswell Seismic Data
    (Springer, 2017) Raji, Wasiu O; Yongxin, Gao; Harris, Jerry, M
    Despite the numerous advantages of crosswell seismic data over surface seismic data, crosswell seismic geophysics is still underutilized and underdeveloped. The factors limiting the full utilization of crosswell data include the lack of standardized methods for processing and imaging the data. This is because crosswell data is not completely understood. To improve the understanding of crosswell data, we performed acoustic and elastic modeling of a west Texas carbonate oilfield data using finite difference methods and crosswell geometry. To account for the different wave modes in the field data, we decomposed the full data into its constituent wave modes. Results of the forward modeling show that elastic synthetic data is a better representation of crosswell field data than the popular acoustic synthetic data.Wavefield decomposition gave insight into the time-space kinematics behavior of the different wave modes that constitute the full data. Overall, the study improved our understanding of crosswell field data. The learning from this study has been utilized to performdatadriven reflection enhancement processing where the discerned characteristic of different seismic arrival is utilize to suppress unwanted and enhanced the desired wave modes. The processing reduced the complex data to only up-going P-P reflections that can be imaged to reveal the subtle geological structures of the oilfield.