Browsing by Subject "Geological modeling"

Now showing 1 - 4 of 4

Assessing reservoir performance and modeling risk using real options
(2012-05) Singh, Harpreet; Srinivasan, Sanjay; Lake, Larry W.
Reservoir economic performance is based upon future cash flows which can be generated from a reservoir. Future cash flows are a function of hydrocarbon volumetric flow rates which a reservoir can produce, and the market conditions. Both of these functions of future cash flows are associated with uncertainties. There is uncertainty associated in estimates of future hydrocarbon flow rates due to uncertainty in geological model, limited availability and type of data, and the complexities involved in the reservoir modeling process. The second source of uncertainty associated with future cash flows come from changing oil prices, rate of return etc., which are all functions of market dynamics. Robust integration of these two sources of uncertainty, i.e. future hydrocarbon flow rates and market dynamics, in a model to predict cash flows from a reservoir is an essential part of risk assessment, but a difficult task. Current practices to assess a reservoir’s economic performance by using Deterministic Cash Flow (DCF) methods have been unsuccessful in their predictions because of lack in parametric capability to robustly and completely incorporate these both types of uncertainties. This thesis presents a procedure which accounts for uncertainty in hydrocarbon production forecasts due to incomplete geologic information, and a novel real options methodology to assess the project economics for upstream petroleum industry. The modeling approach entails determining future hydrocarbon production rates due to incomplete geologic information with and without secondary information. The price of hydrocarbons is modeled separately, and the costs to produce them are determined based on market dynamics. A real options methodology is used to assess the effective cash flows from the reservoir, and hence, to determine the project economics. This methodology associates realistic probabilities, which are quantified using the method’s parameters, with benefits and costs. The results from this methodology are compared against the results from DCF methodology to examine if the real options methodology can identify some hidden potential of a reservoir’s performance which DCF might not be able to uncover. This methodology is then applied to various case studies and strategies for planning and decision making.
Geologic characterization and modeling for quantifying CO₂ storage capacity of the High Island 10-L field in Texas state waters, offshore Gulf of Mexico
(2019-09-12) Ramirez Garcia, Omar; Chuchla, Richard J. (Richard Julian); Meckel, Timothy Ashworth
Carbon dioxide capture and storage (CCS) is a promising technology for mitigating climate change by reducing CO₂ emissions to the atmosphere and injecting captured industrial emissions into deep geologic formations. Deep subsurface storage in geologic formations is similar to trapping natural hydrocarbons and is one of the key components of CCS technology. The quantification of the available subsurface storage resource is the subject of this research project. This study focuses on site-specific geologic characterization, reservoir modeling, and CO₂ storage resource assessment (capacity) of a depleted oil and gas field located on the inner continental shelf of the Gulf of Mexico, the High Island 10L field. lower Miocene sands in the Fleming Group beneath the regional transgressive Amphistegina B shale have extremely favorable geologic properties (porosity, thickness, extent) and are characterized in this study utilizing 3-D seismic and well logs. Key stratigraphic surfaces between maximum flooding surfaces (MFS-9 to MFS-10) demonstrate how marine regression and transgression impact the stacking pattern of the thick sands and overlying seals, influencing the overall potential for CO₂ storage. One of the main uncertainties when assessing CO₂ storage resources at different scales is to determine the fraction of the pore space within a formation that is practically accessible for storage. The goal of the modeling section of this project is to address the uncertainty related to the static parameters affecting calculations of available pore space by creating facies and porosity geostatistical models based on the spatial variation of the available data. P50 values for CO₂ storage capacity range from 37.56 to 40.39 megatonnes (Mt), showing a narrow distribution of values for different realizations of the geostatistical models. An analysis of the pressure build-up effect on storage capacity was also performed, showing a reduction in capacity. This research further validates the impact of the current carbon tax credit program (45Q), applied directly to the storage resources results for the High Island field 10L using a simple NPV approach based on discounted cash flows. Several scenarios are assessed, where the main variables are the duration of the applicability of the tax credit, number of injection wells, and total storage capacity. Results are measured in terms of the cost of capture required for a project to be economic, given previous assumptions.
Physical models and natural examples of fold interference
(1995-08) Johns, Mary Katherine; Mosher, Sharon, 1951-
Fold interference is used to identify areas of polyphase deformation and to evaluate their deformation history. In this study, dynamically scaled physical models were shortened in two orthogonal directions in a centrifuge to test the effects of material properties and deformation history on the style of fold interference. Models shortened sequentially demonstrate that rheological contrast strongly controlled the interference style. Models with low competence contrast layering had circular to elliptical interference patterns. In addition to folding, the models accommodated strain by significant layer-parallel shortening. Models with high competence contrast layering had folded early hingelines and axial surfaces. In plan view, the second-generation folds were lobate-cuspate to box-style, and the axial traces of the box folds formed conjugate pairs. Models shortened coevally had distinct structural styles from the sequentially shortened models, as illustrated by serial Computed Tomographic (CT) X-ray scans. High competence contrast models were dominated by irregular elliptical to crescent map-shapes in the center of the models. Near the model edges, folds had straight hingelines, parallel to the boundaries. Coevally shortened models faulted and fractured less commonly than did the sequentially shortened models. Although some of the structures resembled superposed folds, the regionally inconsistent fold orientations and overprinting relationships, as well as the predominance of dome-and-basin over crescent-style interference differentiated coeval from sequential fold interference. For both deformation histories, gravitational body forces effectively damped the vertical amplification of folds, thereby accentuating the change in fold style with depth. Comparison of results from these models with regional-scale natural examples demonstrates that buckle-fold interference occurs in a wide range of rock types and tectonic settings. Comparison of the sequentially shortened, high competence contrast models with the Narragansett Basin, Rhode Island, suggests an alternative tectonic model for its third phase (D3) of Alleghenian deformation. According to previous tectonic models, D 3 sinistral shear produced both E-W trending folds and sinistral kinematic indicators. I propose that the same features could be caused by N-S shortening, which is locally partitioned into a NE-trending megakink band.
Pre-stack inversion for porosity estimation from seismic data in an oil field, Eastern Saudi Arabia
(2008) AlMuhaidib, Abdulaziz Mohammad; Sen, Mrinal K.
The main objective of seismic inversion is to obtain earth model parameters from seismic reflection data. In other words, it is the process of determining what physical characteristics of rocks and fluids (i.e., P-impedance, shear impedance, and density) could have produced the seismic record. The aim of this study is to obtain reservoir properties, such as porosity both at the well locations and in the inter-well regions from seismic data and incorporated well logs. The target is a Jurassic carbonate reservoir from an oil field located to the East of Saudi Arabia. The purpose was to investigate the reliability of inferring the elastic properties (Zp, Zs, ρ) from seismic data in this field, and to build a geologic framework for flow simulation for better reservoir production forecasting and management. The seismic data were processed with special attention to preserving the true reflection amplitudes, and were time migrated before stack. Residual moveout from multiples after NMO, however, is almost horizontal at near offset, and constructively add to the stacked amplitude. Therefore, we applied a pre-stack inversion technique on the seismic data, after careful processing, including removal of residual internal multiples. Such an inversion incorporates all of the offsets to obtain an optimum acoustic impedance model. We also investigated the stability of inverting shear impedance and density in the field of study. The seismic inversion results were overall very good and stable for P-impedance. The match between borehole log and seismic impedance profiles was excellent for the high-contrast events and variable for the low contrast in acoustic impedance, depending on the location within the field. Inverted shear impedance results were less stable compared to P-Impedance, while density was totally unstable and has not been resolved. In general, areas of poor inversion coincided with the zones of poor quality seismic data. The borehole log data showed a good impedance-porosity relationship. The Raymer-Hunt-Gardner impedance-porosity empirical relation fits the borehole data very well. Thus, I used the Raymer-Hunt-Gardner relation, with coefficients for this field derived from the log data, to convert inverted acoustic impedance into a porosity model for the field. Based on the new quantitative seismic reservoir characterization, I was able to identify additional areas of potentially good reservoir quality