JOURNAL OF GEOTECHNICAL GEOLOGY (APPLIED GEOLOGY)
Year:2009 | Volume:5 | Issue:3|Papers Count:10

Porosity and permeability are the most important hydrocarbon reservoir parameters. In the present study, intelligent soft computing neural networks that nowadays are widely used in petroleum industry were are used for prediction of porosity and permeability in Asmari formation the Asmari Formation. In this study MATLAB software are is used to handle neural networks core and well logs data, including porosity and permeability. These networks were developed by using error-back propagation algorithm within feed-forward networks. After comparing the measured and network predicted results, the parameters of the ANN (Artificial Neural Networks) were adjusted for a desired network.Correlation obtained between core results and ANN predicted porosity and permeability are 0.92 and 0.82, respectively.These results show that intelligent neural network models have predicted porosity and permeability successfully.Finally, the above mentioned network was generalized to the third well which had no core data.

In this research, ground motion analysis and site effect ground motion and site effect analyses were conducted in the south of Yazd city by using geotechnical data, down hole seismic profiles, strong ground motion and accelerograms with regard to changes in frequency. To estimate the soil non-elastic response and equivalent linear behavior of soil, an iterative loop was utilized. Non-linear behavior of stress-strain means shear modulus change in different ways. The maximum of acceleration records of ground motion in bedrock for a 475 years return period are used for this research work is 0.219 g. Taking the above mentioned return period into consideration, for this borehole the values of resonance frequency and alluvium resonance ratio were measured as 3.4 and 1.4, respectively. On the basis of average resonance ratios and frequencies obtained from all the models, the amplification of shear waves are intensified in frequencies 3 to 4 Hz with a an amplification ratio 1.6 Vs 30, mean is 360 m/s.

From the point of view of seismicity, the Gole-Gohar mining area seems to be active because the mine is located in an area crossed by two large active faults. Further, the Main Zagros Thrust, the High Zagros thrusts, the Naien- Baft fault and the Dehshir fault are all located within a distance of in a 100 km distance from the Gole-Gohar mine, thus increasing the possibility of a great earthquake in this region.

Considerable damages are annually reported due to the slope instabilities across the country. Many factors directly affect or trigger the instabilities in which include lithology, geological structures, slope angle, drainage pattern, and elevation. The potential of slope stability in Kangan Anticline is considered in this paper. The Anticline is located in Bushehr Province where many gas producing wells are located. Slope instability hazard zonation in the middle part of the Kangan anticline is evaluated according to the Anbalagan Method. Many causative factors including lithology, slope degree, geological structures, elevation, hydrogeology, land-use and land-cover are considered in this analysis. The area is classified with regard to slope instabilities, into the four zones, namely "low hazard", "medium hazard", "high hazard" and "very high hazard". Most dominant types of hazard are identified as medium and high potential with surface coverage of 42% and 49% respectively. The very high and low potential hazard only covers 6.5% and 2.5% of the studied area. The Pabdeh and Gurpi Formations and also Quaternary deposits are identified as very high hazard zones with surface coverage of 47%.

To evaluate the sedimentation ratio of the proposed area of study area to be studied, i.e. the basin of the Jajrud River at the upper level of the Latian dam, the present study has prefered multivariable regerssion regression method has been preferred. Therefore, by this reason, in order to identify the most important physiographic agent which is effective in flooding, flood-debi equation and then debi-sediment for each sub-basin were obtained by applying these factors to the regression model. Reveiwing Reviewing the equations and putting them with the proposed parameters, the maximum flood-debi were was calculated for sub-basins. Consequenlty Consequently, these equations also helped in presenting a suitable way for anticipated flood-debi or the transported sediment loads. Likewise, for sub-basins (Amameh, Kund and Afjeh) whose data were accessible simultaneously with debi-sediment equations for a longer period of time, the transoported transported sediment loads are acquired only when the rive-debi reaches to its peak. The acquired results indicate that that the Ahar sub-basin has the lowest strength of sedimentation and the best option for water closet because of its lengthiest concentration time, high elongation, mild steep steepness and the lowest condensation level.Similarly, the highest strength of sedimentation is related to the Amameh sub-basin, where the sediment production is about 7853.3 tones tons every day. Wider steep of the Steeper and lengthier basins, bigger length, the lowest shorter concentration time and higher condensation could be presented as the other effective factors in this process.

The area of the Ghareh-Aghaj river watershed basin, from the source area to the Kavar dam-site at down-stream, is estimated to be about 1600 km2. The river flows in a southeasterly direction, passing by 20 km southwest of Shiraz. In this research, the total sediment yield of the Ghareh-Aghaj river to the dam-site was calculated by using hydraulic and sediment logical methods. These methods indicate flow depth, channel slope, river width, flow velocity, angle of repose and particle size characteristics (d10, d30, d60 and d90). Furthermore, the water temperature and the kinematic viscosity of the water, due to its effects on the movement of sediments, were determined. The suspension load rate of the river was estimated at 765040 ton/year by using the Yang Method. This research shows that the bed-load rate of the river is about 21% of the suspension load according to the Meyer-Peter & Muller Method.

Continental strike slip faults, which are important deformation elements in the continents, can cause large-magnitude earthquakes. As an example of these continental fault systems in the Zagros-Makran-Central Iran transitional zone, the Sabzevaran-Jiroft fault system consumes the shear between the Zagros and Makran. The Sabzevaran fault with a length of 150 km shows various evidences of active faulting in the Quaternary. The cumulative displacement along the Sabzevaran fault is measured 130 m for the last 42 KY with a horizontal slip-rate of about 2.98±0.75 mm/yr. The Jiroft fault with a length of 130 km delimits the western boundary of the Jazmurian depression. This fault caused a separation of about 49 m and 132 m in the 22 KY and 42 KY alluvial fan deposits. The average horizontal slip-rate of the fault calculated about 2.7±0.7 mm/yr.Seismicity of the Sabzevaran region indicates sparsely spatial distribution of low-magnitude earthquakes. According to these study, the Maximum Credible Earthquake (MCE) with a magnitude of 6.4 indicate a recurrence time of 1300 yr. Comparison of recurrence time of large- to medium-magnitude earthquakes- derived from historical and instrumental earthquake catalogues- with the mean annual slip-rate of the active faults in the Sabzevaran region, we suggest lack of fault locking or a continuous fault creep along the Sabzevaran-Jiroft fault system.

The slopes of the edges of the Rajdoon River in the north of Ganaveh have the high potential of slipping slippage. The occurrence of strong earthquakes increases this potential of instability, severely. The depositions of downstream which were formed from siltstone, has have the ability to produce the circular slips, but the depositions upstream which were formed from the mudstone has the ability to produce the are capable of producing columnar- plane slips. In these cases, the occurrence of an earthquake with the horizontal speed (velocity) of more than 0.14 g (DBL) in the area of Rajdoon causes the instability of slopes with the gradient of more than 20 degrees. These slips block the way of water flow and also would lead to the formation of natural dams in the way of stream stream bed. The result of This event and the breaking of dams would result to the in great flood waters and also the destruction of some parts of Ganaveh city.