River regulation and reservoirs can provide a variety of services including flood protection, flow management and flow augmentation, however, there is increasing concern regarding these effects on downstream lotic environments and aquatic ecosystems. While a growing body of knowledge regarding the ecological effects of regulation exists, little is still known about the effects of reservoirs and their management strategies on benthic macroinvertebrates in the Grand River watershed and further research is needed for sufficient watershed planning and reservoirs management practices. In this study, the downstream effects of river regulation and reservoir on aquatic ecosystems were evaluated using benthic macroinvertebrate biomonitoring techniques. Field research was conducted on five reservoirs (three deep release and two surface release) located within the Grand River watershed during three sampling periods in May-June, August and November, 2006. Benthic macroinvertebrates were collected using a T-sampler in reaches upstream and downstream of each reservoir across stream riffles perpendicular to stream flow direction. Changes in benthic macroinvertebrate community structure were quantified using nine summary indices. Downstream of reservoirs, invertebrate abundance, Hilsenhoff’s Biotic Index (HBI) values and Isopoda and Chironomidae abundance increased, while taxa richness, Ephemeroptera, Plecoptera and Trichoptera (EPT) taxa and Ephemeroptera abundance decreased. Although comprehensive chemical testing was not conducted in the present study, changes in benthic macroinvertebrate abundance and diversity and a review of literature suggests that downstream ecosystems may have been impacted by changes in water quality, thermal alterations and modifications to habitat diversity induced by impoundments and most noticeably deep release reservoir designs. Benthic macroinvertebrates are useful biological indicators and monitoring tools to assess the effects of reservoirs and their management strategies on downstream ecosystems. Information gained from this study may assist policymakers and planners in monitoring, developing and implementing improved watershed planning and reservoir management decision making.

River regulation and reservoirs can provide a variety of services including flood protection, flow management and flow augmentation, however, there is increasing concern regarding these effects on downstream lotic environments and aquatic ecosystems. While a growing body of knowledge regarding the ecological effects of regulation exists, little is still known about the effects of reservoirs and their management strategies on benthic macroinvertebrates in the Grand River watershed and further research is needed for sufficient watershed planning and reservoirs management practices. In this study, the downstream effects of river regulation and reservoir on aquatic ecosystems were evaluated using benthic macroinvertebrate biomonitoring techniques. Field research was conducted on five reservoirs (three deep release and two surface release) located within the Grand River watershed during three sampling periods in May-June, August and November, 2006. Benthic macroinvertebrates were collected using a T-sampler in reaches upstream and downstream of each reservoir across stream riffles perpendicular to stream flow direction. Changes in benthic macroinvertebrate community structure were quantified using nine summary indices. Downstream of reservoirs, invertebrate abundance, Hilsenhoff’s Biotic Index (HBI) values and Isopoda and Chironomidae abundance increased, while taxa richness, Ephemeroptera, Plecoptera and Trichoptera (EPT) taxa and Ephemeroptera abundance decreased. Although comprehensive chemical testing was not conducted in the present study, changes in benthic macroinvertebrate abundance and diversity and a review of literature suggests that downstream ecosystems may have been impacted by changes in water quality, thermal alterations and modifications to habitat diversity induced by impoundments and most noticeably deep release reservoir designs. Benthic macroinvertebrates are useful biological indicators and monitoring tools to assess the effects of reservoirs and their management strategies on downstream ecosystems. Information gained from this study may assist policymakers and planners in monitoring, developing and implementing improved watershed planning and reservoir management decision making.

The petroleum industry commonly uses single-layer models to characterize and forecast long-term production in tight gas reservoir systems. However, most tight gas reservoirs are layered systems where the permeability and porosity of each layer can vary significantly, often over several orders of magnitude. In addition, the drainage areas of each of the layers can be substantially different. Due to the complexity of such reservoirs, the analysis of pressure and production history using single-layer analyses techniques provide incorrect estimates of permeability, fracture conductivity, drainage area, and fracture half-length. These erroneous values of reservoir properties also provide the reservoir engineer with misleading values of forecasted gas recovery. The main objectives of this research project are: (1) to demonstrate the typical errors that can occur in reservoir properties when single-layer modeling methods are used to history match production data from typical layered tight gas reservoirs, and (2) to use the single-layer match to demonstrate the error that can occur when forecasting long-term gas production for such complex gas reservoirs. A finite-difference reservoir simulator was used to simulate gas production from various layered tight gas reservoirs. These synthetic production data were analyzed using single-layer models to determine reservoir properties. The estimated reservoir properties obtained from the history matches were then used to forecast ten years of cumulative gas production and to find the accuracy of gas reserves estimated for tight gas reservoirs when a single-layer model is used for the analysis. Based on the results obtained in this work, I conclude that the accuracy in reservoir properties and future gas flow rates in layered tight gas reservoirs when analyzed using a single-layer model is a function of the degree of variability in permeability within the layers and the availability of production data to be analyzed. In cases where there is an idea that the reservoir presents a large variability in ‘’k”, using a multi-layer model to analyze the production data will provide the reservoir engineer with more accurate estimates of long-term production recovery and reservoir properties.

Design of matrix acidizing treatments of carbonate formation is still a challenge although extensive research has been done on it. It is necessary to estimate acid distribution along the wellbore. This estimation is very important especially for the case where the reservoir properties vary along the wellbore. This work provides development and application of an apparent skin factor model which accounts for both damage and mobility difference between acid and gas. Combining this model with a conventional acid placement model, we develop an acid placement model for vertically extensive, multilayer gas reservoirs. A computer program is developed implementing the acid placement model. The program is used to simulate hypothetical examples of acid placement for vertically extensive, multilayer gas reservoirs. This model will improve matrix acidizing for gas reservoirs and enable realtime monitoring of acid stimulation more accurately.

Thesis (Ph. D.)--University of Queensland, 2001. / Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Supervisors: William L. Fisher and Bob A. Hardage. Vita. Includes bibliographical references. Also available from UMI.

The folded and thrusted Mesozoic clastic sequence of the Canadian Rocky Mountain foothills forms important hydrocarbon reservoirs. Understanding the distribution of natural fractures, their evolution, and timing of formation relative to the evolution of the fold-and-thrust system could potentially improve exploration and development outcomes in these otherwise tight unconventional reservoirs. However, the formation of fractures and their timing relative to folding and thrusting have remained unclear. I investigated the relation between folding and fracture formation in the Upper Cretaceous Cardium Sandstone by combining field structural observations and kinematic modeling of the fold-and-thrust belt evolution. I explored the relationship between fracture intensity and fracture strain with structural position by analyzing fracture spacing or frequency and aperture data collected along outcrop and micro-scanlines in the backlimb, in the forelimb close to the crest, and in the steeper dipping forelimb away from the crest of the Red Deer River anticline. Fracture frequency and aperture data collected both at the outcrop and micro scales indicate that variation in fracture strain is small across these three structural domains of the fold, with somewhat lower fracture intensity in the forelimb close to the crest. These fracture strain measurements are qualitatively consistent with calculated horizontal strain in the tectonic transport direction obtained through kinematic numerical models that simulate fold development associated with slip along the underlying Burnt Timber thrust. The models predict roughly similar amount of horizontal extension in both the back and forelimbs, and somewhat lower extension in the upper forelimb during early development of the Red Deer River anticline. Fracture formation early during fold development is consistent with the field structural observations of shear reactivation during later stages of folding. This combined kinematic modeling and field structural study demonstrates that deforming fold and thrust belts can undergo a complex evolution of bed-parallel extension in both space and time, resulting in spatially variable fracture formation in such structurally complex subsurface reservoirs. / text

Discrete Fracture Networks (DFN) models have long been used to represent heterogeneity associated with fracture networks but all previous approaches have been either in 2D (assuming vertical fractures) or for simple models within a small domain. Realistic representation of DFN on field scale models have been impossible due to two reasons - first because the representation of extremely large number of fractures requires significant computational capability and second, because of the inability to represent fractures on a simulation grid, due to extreme aspect ratio between fracture length and aperture. This thesis presents a hierarchal approach for fracture modeling and a novel random walker simulation to upscale the fracture permeability. The modeling approach entails developing effective flow characteristics of discrete fractures at micro and macrofracture scales without explicitly representing the fractures on a grid. Separate models were made for micro scale and macro scale fracture distribution with inputs from the seismic data and field observations. A random walker simulation is used that moves walkers along implicit fractures honoring the intersection characteristics of the fracture network. The random walker simulation results are then calibrated against high-resolution flow simulation for some simple fracture representations. The calibration enables us to get an equivalent permeability for a complex fracture network knowing the statistics of the random walkers. These permeabilities are then used as base matrix permeabilities for random walker simulation of flow characteristics of the macro fractures. These are again validated with the simulator to get equivalent upscaled permeability. Several superimposed realizations of micro and macrofracture networks enable us to capture the uncertainty in the network and corresponding uncertainty in permeability field. The advantage of this methodology is that the upscaling process is extremely fast and works on the actual fractures with realistic apertures and yields both the effective permeability of the network as well as the matrix-fracture transfer characteristics. / text

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