The effects of planting methods for plant establishment of grass were studied in this work. Three important grass species in Iranian rangelands are Agropyron elengatum, A. desertorum and Bromus tomentellus. The investigated planting methods were broadcasting, shallow drilling and deep drilling. The experiment was carried out in split plot experimental design. The main factors were planting methods and the sub factors were grass species. They were planted in three replications and in two years. In broadcasting, a 28-blade disk covered the seeds. A Rau experimental planter was used in shallow and deep drilling methods. In shallow drilling method furrow openers were not used on planter. For deep drilling furrow openers were installed on planter. This study was carried out in 1997and 1998.In the broadcasting planting method, the seedling was not established properly. The best seedling establishment was in shallow drilling method. The seedlings were established intermediate in deep drilling method.

Fluid properties with constant improvement in efficiency have been noticeable as important criteria in drilling operation. The main drilling fluid properties highly depend on utilization of new polymers with high efficiency in drilling fluid composition. In this paper, the performance of a new polymer, called partially hydrolyzed polyacrylamide polymer (PHPA), is studied which has recently entered the drilling fluids industry in Iran. Hence viscosity property, fluid loss control and shale inhibition of this polymer have been evaluated based on an international standard method of API-13-I by considering the drilling and operational priorities of the country. Then the thermal effect, salt contaminants such as sodium chloride, calcium chloride, magnesium chloride and pH tolerance effect as major pollution indicators are also investigated in relation to polymeric fluid properties. The results obtained by the tests show that furthermore polymer PHPA increases rheological properties (apparent viscosity, plastic fluidity and yield point) and it plays important role in increases in fluid loss. This polymer has also demonstrated acceptable resistance toward sodium chloride contaminants, but its efficiency decreases toward calcium and magnesium ion contaminants. The thermal tests show that polymer PHPA has high thermal stability up to 150°C. This polymer improves shale inhibition property and by encapsulation mechanism prevents dispersion of shale cuttings into the drilling fluid system as it stops any changes in fluid properties which will finally results in wellbore stability.

In this paper, the effect of surface curvature on calibration coefficients of the Hole-Drilling method has been studied. Firstly, an FE simulation of the drilling process has been modeled for a flat surface. Then, the simulation has been implemented on a cylinder with different diameters and the calibration coefficients have been extracted. In all analyses, the stain-gauge rosette and hole diameter remain constant and mesh removal in the drilling simulation was achieved in eight increments. The comparison of simulation results and standard published calibration coefficients data for a flat surface show an acceptable error equal to 2.8 variation of errors between 0.6 to 6.2.

One of the most intense and expensive problems during drilling operations is the loss of circulation, which should be addressed and mitigated immediately. Lost circulation could result in several consequences, including wellbore instability, poor hole cleaning, stuck pipe, well control issues and formation damage. Cross-linkable polymer gels play an important role in plugging loss zones. Coating the cross-linker on the nanomaterials extends the length of the cross-linker and forms a stronger network between the polymers. The nanocomposite gel consists of a crosslinked gel by nano-crosslinkers. In this study, the effect of parameters such as the type of crosslinker, temperature and salinity on the performance of the gel, as well as re-crosslinking efficiency at high shear rates and the stability of the gel with time, was investigated and evaluated. Using dynamic stability tests, the maximum amount of pressure that gels can withstand to prevent further drilling fluid loss in highly permeable or fractured formations, was examined. Also, empirical modeling was done by using response surface methodology. The obtained model predicts the viscosity of nanocomposite gel with an accuracy of 86% within the range of input parameters. According to the experimental results, the presence of nano crosslinker in the gel causes the self-healing ability of the formed gel at high shear rates. The nanocomposite gel has a better performance than the hybrid gel at high temperatures and also in the presence of destructive ions, which is due to the high efficiency of the nano-crosslinker in in creating the gel network. In addition, the presence of nano-crosslinker in the gel increases the maximum sealing pressure of gels in plugging highly permeable and fractured formations. Due to the complete rupture of nanocomposite gel in hydrochloric acid, the possibility of formation damage is reduced.

DTH drilling is a reliable method for drilling in medium to hard geological structures. Considering the country's need for different types of drilling bits in various industries, with development of knowledge and production of them, it can limit the vast importation of these products. In this study, process of bit/rock collision taking into account interaction between the insert/body and stresses resulting from interference fit is simulated to determine proper tolerance for fitting, which is the most important factor limiting the life of drilling bit. Simulations were carried out taking account rotary motion of bit in addition to impact in single-insert condition with different angles of collision and also in a 3. 5 inch bit with 13 inserts. Mechanical properties of specimens made of DIN1. 6580 steel, used for manufacturing of bit body, were obtained through experiments. Then, in order to validate and also obtain appropriate mesh size, results of pin-hub interference fit simulations with selected parameters were compared to Lame's analytical method. Results show that interference tolerance and speed and angle of impact have great influence on stresses and process forces. In case of 1. 2% of interference, stresses in bit body are about to reach material strength. In the case of 0. 9% and 0. 6%, certain amount of plastic strain is also created in the body. The results of this study is greatly helpful in choosing fitting tolerance of inserts into bit body during manufacturing process.

Wellbore instability during the drilling of shale formation is the most troublesome and the costly issue facing drilling engineers. Early attempts to control these instabilities are the usage of appropriate additives in water based drilling fluids. This study aims to introduce a new water-based drilling fluid amine-based additive called tallow amine ethoxylate in order to hydration decrease and stability increase of shale formation. Shale hydration Inhibition performance of tallow amine ethoxylate was investigated through different experiments under various experimental conditions. The results showed that bentonite particles are not capable of being hydrated or dispersed in the mediums containing tallow amine ethoxylate, and also tallow amine ethoxylate had comparable and competitive inhibition performance with potassium chloride as a common shale stabilizer in drilling industry. Tallow amine ethoxylate is also compatible with other common drilling fluid additives. Some functional groups exist in tallow amine ethoxylate which are capable of forming hydrogen bonding with surfaces of bentonite particles, leading to decrease of water adsorption on bentonite particles’ surfaces which results in bentonite swelling reduction.

Aim of the project is efficiency increase of hard rocks destruction at borehole bottom by developing drilling mud solution and evaluation of its influence on drilling process. The article presents the results of studies directed on studying of drilling mud composition (the choice of reagent concentrations, taking into account the filtration properties, structural and rheological parameters, study of the temperature effect influence on the quality of the solution). Experiments of metallic indenter penetration into the glass sample at various number of strikes in the water and surfactant solutions are presented in the article. Paper also offers investigation devoted to development of clayless mud solution with surfactant addings, which will allow increase of hard rocks destruction efficiency. Results of industrial test trials of developed mud solution are also represented, showing implementation of developed drilling mud composition to increase productivity of drilling operations by maintaining high drilling speed and advance per bit.

Sustainable production of sufficient energy to power the world’s economy with a minimum environmental footprint has been one of the most significant challenges for the decades. Geothermal energy has been considered as one of the promising options to meet the world’s future energy demand. The cost of drilling geothermal wells is between 35% and 50% of the total investment cost for the new high-temperature geothermal plants. This “up front” cost makes the geothermal plants more expensive to build than the conventional plants, and because of this and the perceived risk, a lot of attention has been focused on reducing this cost.This paper attempts to minimize the cost of drilling deep wells such as AG-119X, in Egypt of 20060 ft. in depths; in this well, the actual cost was more than the proposed by about five million USD. The actual cost of the drilling operation has been analyzed and compared with the proposed; by observing the cost of each drilling item, it was found that the power drive tools in the bottom hole assembly such as the downhole motor with Rotary Steerable drilling system (RSS) or turbodrill hydraulic downhole motor is the most costly element of the drilling operation in 8.5 holes, which tack thirteen trips in every trip with a new bit, and it was found that the turbodrill hydraulic downhole motor was costly effected in drilling the shush section, in this, and can save around 1756999 USD;  this paper is a road map for reducing the cost of drilling geothermal wells.