The Zagros fold-thrust belt results from the continent-continent collision between the Arabian margin and the Eurasian plate following the closure of the Neo-Tethys Ocean during the Tertiary. Despite some ongoing controversies about the timing of the onset of the collision there is little doubt that the main episode of the cover shortening in the Zagros folded belt occurred since about 10 Ma as suggested by the youngest folded strata of the Agha Jari red marls. Shortening by about 70 km derived from balanced sections across the Zagros folded belt, yields shortening rates of 7 km Ma-1 consistent with the present-day rates of 0.7 cm yr-1 based on GPS studies. A major unconformity between the Agha Jari formation and the Bakhtyari conglomerates indicates that cover shortening decreased or ceased 5 Ma ago. During or since the deposition of the Bakhtyari Formation, the Zagros fold belt underwent a regional uplift whose origin still remains enigmatic. The deformation is characterized by periodic folding with axial lengths sometimes greater than 200 km. This fold geometry is outlined by the limestone beds of the Asmari Formation, which is one of the main oil reservoirs in the Zagros. The Zagros also serves as the main originating headspring of the rivers running into the Persian Gulf and Oman Sea watersheds. Among all these rivers, the major ones are: Arvand Rud, Gamasb, Karun, Rajah, Zaal and Marun join and form Jarahi, Seymareh, Qareh Aqhaj, Zohreh, Dalaki, Mend, Shur, Minab, Mehran and Naband. Therefore, the Zagros region has high potential for dam construction to control surface water for electric energy, water supply for irrigation of agricultural lands and land reclamation. Among various formations in the Zagros region, the Asmari Formation limestone with relatively exclusive characteristics such as rigidity and morphology is a suitable rock foundation for dams in the Zagros range. It should be considered that the Asmari limestones constitute a series of double plunging, asymmetrical folds with northwest-southeast trend and that the southern flanks are steeper than the north-eastern ones (70° to 90º, locally reversed). Due to varying inclinations, there are much more curvatures of strata in the southwestern flanks of folded structures, with different characteristics of the rock mass in the two flanks of the anticlines. The anticlines, particularly in the Asmari Formation, contain tension-induced, open fracturing which has introduced significant secondary permeability. Engineering geological investigations indicate that there is a clear relationship between rock mass characteristics of the Asmari Formation and tectonic activities such as various tilting and curvature rates of strata at folded structures in the Zagros Mountain range. In this regard it should be considered that the upper and middle units of the Asmari Formation that constituted the main dam foundation rock mass on the northern flanks are influenced by karstification processes which have resulted from aggressive mineral waters. Thus huge karst features and cavities can be observed, where the Gachsaran evaporites stratigraphically overlie Asmari Formation succession limestones. The aggressive mineral waters originating from the Gachsaran Formation play the main role in karstification of the Asmari Formation limestones, whereas the lower Asmari is less influenced by these solutions and karstification processes as it is restricted to where the Karun-3 and Karun-4 dams are situated. Reassessment of available data and geological investigations during this research, lead to a new proposed configuration of engineering characterization of the rock mass for the Asmari formation limestones in the Zagros Region. / Thesis (PhD)--University of Pretoria, 2012. / Geology / unrestricted

Deep slurry injection is a process of solid waste disposal that involves grinding the solid waste to a relatively fine-grained consistency, mixing the ground waste with water and/or other liquids to form slurry, and disposing of the slurry by pumping it down a well at a high enough pressure that fractures are created within the target formation. This thesis describes the site assessment criteria involved in selecting a suitable target reservoir for deep slurry injection. The main goals of this study are the follows: <ul> <li>Identify the geological parameters important for a prospective injection site</li> <li>Recognize the role of each parameter</li> <li>Determine the relationships among different parameters</li> <li>Design and develop a model which can assemble all the parameters into a semi-quantitative evaluation process that could allow site ranking and elimination of sites that are not suitable</li> <li>Evaluate the model against several real slurry injection cases and several prospective cases where slurry injection may take place in future</li> </ul> The quantitative and qualitative parameters that are recognized as important for making a decision regarding a target reservoir for deep slurry injection operations are permeability, porosity, depth, areal extent, thickness, mechanical strength, and compressibility of a reservoir; thickness and flow properties of the cap rock; geographical distance between an injection well and a waste source or collection centre; and, regional and detailed structural and tectonic setup of an area. Additional factors affecting the security level of a site include the details of the lithostratigraphic column overlying the target reservoir and the presence of overlying fracture blunting horizons. Each parameter is discussed in detail to determine its role in site assessment and also its relationship with other parameters. A geological assessment model is developed and is divided into two components; a decision tree and a numerical calculation system. The decision tree deals with the most critical parameters, those that render a site unsuitable or suitable, but of unspecified quality. The numerical calculation gives a score to a prospective injection site based on the rank numbers and weighting factors for the various parameters. The score for a particular site shows its favourability for the injection operation, and allows a direct comparison with other available sites. Three categories have been defined for this purpose, i. e. average, below average, and above average. A score range of 85 to 99 of 125 places a site in the ?average? category; a site will be unsuitable for injection if it belongs to the ?below average? category, i. e. if the total score is less than 85, and the best sites will generally have scores that are in the ?above average? category, with a score of 100 or higher. One may assume that for sites that fall in the ?average? category there will have to be more detailed tests and assessments. The geological assessment model is evaluated using original geological data from North America and Indonesia for sites that already have undergone deep slurry injection operations and also for some possible prospective sites. The results obtained from the model are satisfactory as they are in agreement with the empirical observations. Areas for future work consist of the writing of a computer program for the geological model, and further evaluation of the model using original data from more areas representing more diverse geology from around the world.

Deep slurry injection is a process of solid waste disposal that involves grinding the solid waste to a relatively fine-grained consistency, mixing the ground waste with water and/or other liquids to form slurry, and disposing of the slurry by pumping it down a well at a high enough pressure that fractures are created within the target formation. This thesis describes the site assessment criteria involved in selecting a suitable target reservoir for deep slurry injection. The main goals of this study are the follows: <ul> <li>Identify the geological parameters important for a prospective injection site</li> <li>Recognize the role of each parameter</li> <li>Determine the relationships among different parameters</li> <li>Design and develop a model which can assemble all the parameters into a semi-quantitative evaluation process that could allow site ranking and elimination of sites that are not suitable</li> <li>Evaluate the model against several real slurry injection cases and several prospective cases where slurry injection may take place in future</li> </ul> The quantitative and qualitative parameters that are recognized as important for making a decision regarding a target reservoir for deep slurry injection operations are permeability, porosity, depth, areal extent, thickness, mechanical strength, and compressibility of a reservoir; thickness and flow properties of the cap rock; geographical distance between an injection well and a waste source or collection centre; and, regional and detailed structural and tectonic setup of an area. Additional factors affecting the security level of a site include the details of the lithostratigraphic column overlying the target reservoir and the presence of overlying fracture blunting horizons. Each parameter is discussed in detail to determine its role in site assessment and also its relationship with other parameters. A geological assessment model is developed and is divided into two components; a decision tree and a numerical calculation system. The decision tree deals with the most critical parameters, those that render a site unsuitable or suitable, but of unspecified quality. The numerical calculation gives a score to a prospective injection site based on the rank numbers and weighting factors for the various parameters. The score for a particular site shows its favourability for the injection operation, and allows a direct comparison with other available sites. Three categories have been defined for this purpose, i. e. average, below average, and above average. A score range of 85 to 99 of 125 places a site in the ?average? category; a site will be unsuitable for injection if it belongs to the ?below average? category, i. e. if the total score is less than 85, and the best sites will generally have scores that are in the ?above average? category, with a score of 100 or higher. One may assume that for sites that fall in the ?average? category there will have to be more detailed tests and assessments. The geological assessment model is evaluated using original geological data from North America and Indonesia for sites that already have undergone deep slurry injection operations and also for some possible prospective sites. The results obtained from the model are satisfactory as they are in agreement with the empirical observations. Areas for future work consist of the writing of a computer program for the geological model, and further evaluation of the model using original data from more areas representing more diverse geology from around the world.