AAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain
Porosity Prediction from Seismic - Application in a Giant Offshore Oil-Field in Abu Dhabi, United Arab Emirates
(1) ZADCO, Zakum Development Company, Abu Dhabi, United Arab Emirates.
(2) ExxonMobil Upstream Research Company, Houston, TX.
A recent reprocessing of a large ocean-bottom-cable (OBC) seismic data set of a giant offshore oil-field in U.A.E. resulted in several significant seismic imaging, signal/noise, and detection improvements of several fault and horizon geometries which included new fault system sets never recognized before. In addition, seismic amplitude fidelity was improved significantly and it has been confirmed by well-ties and subsequent acoustic impedance inversion. This paper will mainly focus on the description of the acoustic impedance inversion and porosity prediction processes. We have developed a new workflow based on the new data set and performed feasibility study. The process mainly consists of four major steps: rock property analysis, impedance inversion, porosity prediction from multi-attribute analysis, and validation based on well data.
Several hundreds of regular wireline and cross dipole sonic logs were acquired and several tens of ultrasonic measurements from core samples were performed across the field. Data was conditioned and analyzed to understand the porosity versus impedance and other rock physics trends. A relative narrow porosity versus impedance trend was observed in the data set, which laid the foundation for our subsequent analysis. Acoustic impedance inversion was performed in Jason by 1) well-to-seismic tie and wavelet estimation, 2) earth model building based on interpretation and well data, 3) band-limited impedance inversion and total impedance derivation. The inversion results, seismic amplitude volume, and seismic stacks were loaded into Hampson-Russell EMERGE where multi attribute analysis was performed and porosity versus impedance and other attributes relationship was established. The porosity volume was then generated across the entire field based on the established relationship.
The porosity volume and extracted maps of several reservoir intervals were validated with well data, where high consistency was observed and the results are being integrated into geological model