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.

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.

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.

The continuous development of global economy with decreasing in available hydrocarbon sources and increasing discovery and extraction costs due to decrease in-situ oil and gas reservoir, displays the necessity of using new techniques for the improve rate of penetration and productivity in well. Nanotechnology has already contributed significantly to technological advances in the energy industries. Nanotechnology has the potential to introduce revolutionary change in drilling industry. Nanotechnology produces nanomaterials with many attractive properties, which can play an important role in intensifying mud cake quality, reducing friction, eliminating differential pipe sticking, maintaining borehole stability, protecting reservoir, and enhancing oil and gas recovery. Nano fluids can be designed by adding nano-sized particles in low volumetric fractions to a fluid. The nano particles modify the fluid properties, and suspensions of nano-sized particles can provide numerous advantages.This paper presents an extensive literature review of assessing the applications of nanomaterials in drilling and drilling fluids, and evaluates the potential technical benefits that these nanomaterials might provide to petroleum development and production.

Introduction: drilling has various methods that from different aspects such as crushing mechanism, type of used energy etc., is divided to several types containing hand held drilling, percussive drilling, cable-tool drilling, rotary (or circular) drilling, percussive-rotary drilling and core drilling. Unlike the Direct circulation drilling system (DC) in the reverse circulation drilling system (RC), the drilling fluid moves the annulus between borehole wall and the drilling pipe and comes back with the drilled pieces along inside the drilling pipe. The exploratory drilling system of RC by conducting powder samples with high purity and fast drilling rate, is a great help to the velocity and accurate of exploration of ore deposits. Samples produced in this method are in the form of soil and rock powdered and rock fragments of the drilled part, which may be dry or with little moisture. The air flow inside the cycle causes the collected powder sample to be often dry but sometimes is wet due to groundwater or drilling mud. drilling is one of the most costly mining processes. Therefore, the most important goal in drilling engineering is to reduce costs, and the best possible decision to optimize the cost of drilling is to choose the best possible drilling method. Based on the field data, cost of drilling for each meter of a soft rock (e. g. travertine) by core drilling and Direct drilling methods are about 3. 3 and 1. 2 times of the RC method, respectively. Also the cost of drilling, for each meter of a hard rock (e. g. granite) by core drilling and Direct drilling methods are about 2. 6 and 1. 3 times of the RC method, respectively. Materials and methods: In the present research, reverse circulation drilling (RC) has been compared with other important, common and practical drilling methods, such as Direct circulation and core drilling methods in terms of various criteria containing drilling (time) rate, price (cost), type and quality of acquired samples and performance efficiency of drilling. Also, as a field study in this research, deep drilled boreholes with RC and core drilling methods in the gold mine of Khomein-Akhtarchi located in the Markazi province, were investigated and compared from different aspects. At the end, the ability to select the most appropriate drilling method among the variety of methods was studied. The study region is located at 25 km northeast of Khomein city in the Markazi province. This region consists of two exploration areas of Zarmadan-Akhtaran1 with the area of 13. 21 square kilometers and Zarmadan-Akhtaran2 with the area of 2. 85 square kilometers. Access to the Akhtarchi gold region is possible through the Khomein-Shahabiyeh (Goldsat)-Mahallat road. In the mining region, the Permian rock complexes include dolomite, dolomitic limestone from brown to dark gray, black Irony sandstone and white to milky limestone known as pds, pdl and pl units in the geological maps. In the studied region, several deep boreholes, most of them by RC and some of them by core drilling methods have been drilled. In general, by now in the Akhtarchi gold zone in the Zarmadan-Akhtaran2 area 54 powder boreholes have been drilled through RC method called by RC1 to RC54. Also, there are 25 core drilling boreholes, 18 boreholes called by BH1 to BH18 in the Zarmadan-Akhtaran1 area and 5 boreholes called by BH1 to BH5 in the Zarmadan-Akhtaran2 area. During drilling operations, Permian and Cretaceous rock units have been encountered. The details of drilling via RC method for 4 boreholes with numbers 50, 51, 53 and 54 have been accurately taken. The measured drilling times were obtained from drilling personnel of the mine through the questionnaire which they were weighted mean if needed. Results and discussion: The average drilling time for each meter of rock in boreholes 53 and 54 is 2: 12 and 2: 54 minutes, respectively. In both cases, the time duration is very short and this feature is one of the advantages of the RC drilling method. The longer average duration of drilling for each meter of rock in the borehole 54 than 53, is due to the depth of the borehole 54 and the hammer problem of the drilling machine during the drilling this borehole. In Table 1, the average duration of drilling operation per meter of rock in the Akhtarchi gold mine is given according to the type of rock (lithology) at definite depth intervals, on the basis of field studies. According to this table data, the duration of the drilling for each meter of rock in the greater depths increases that the reasons for increasing the duration of drilling for each meter of rock in greater depths are the difficulty of drilling due to the increasing length of rig, the reduction of transient energy to the bit, the probability of greater borehole declination, compaction increasing and as a result increasing the strength of rocks and more hydrostatic and lithostatic pressures in the great depths meanwhile at a great depth, the probability of capturing the drilling rig is too high. Also the cost (the time price) of drilling per meter of rock in this mine based on the dip and depth of drilling is about 1300 to 2000 thousand Rials by the RC method, against 2620 to 4250 thousand Rials by the core drilling method. The results of the present research indicate that the RC drilling in comparison with other drilling methods, especially conventional and applied ones in terms of drilling costs and drilling rate (time) is highly desirable while is desirable regarding depth of drilling, the type and quality of the acquired samples and the overall efficiency of drilling performance. Although the core drilling method with the ability to drill very deep boreholes obtaining cores in terms of the type and quality of the acquired samples, as well as the depth of the drilling is the most desirable, but for exploration drilling (especially in the detailed exploration stages), deposits with low-grade and very little mineral indices (like gold mine of Khomein-Akhtarchi), and hence the large sample sizes are needed, employing RC drilling method having comparative advantages is economic. Conclusion: Regarding the use of RC drilling method in the case study, the gold mine of Khomein-Akhtarchi, it was found that the RC method compared to the core drilling method, in terms of the duration of drilling operations or the speed of advance (the rate of penetration in the rock), drilling costs and efficiency of performance is desirable. Also, according to the type of mineral deposit (gold type), which is low-grade and the indices of the mineral are very low, therefore the large sample sizes are needed, thus, in terms of the type of obtained samples, employing RC drilling method in this case, is accounted a very important advantage related to the DC method (in terms of accuracy) and core drilling method (in terms of cost). The results of this research are useful for all users of drilling operations, including drilling engineers and technicians, engineering geology and geotechnical practitioners, mineral exploration engineers, groundwater aquifers and hydrocarbon reserves (oil and gas) to choose the optimal drilling method under different environmental and economic conditions based on criteria such as the purpose of drilling operations, costs, progress rate, type and quality of the yielded samples and the efficiency of drilling operation. Also, the use of RC drilling method has the advantages over the other drilling methods to be suggested for exploration of low-grade deposits such as gold, silver and copper, especially in the final stages such as detailed and mining exploration.

Today, pilot wells are used for sampling the layers of the earth during deviation drilling. In order to reduce costs and facilitate operations in situations where it is not possible to use a pilot well for coring, coring studies are carried out in a deviant manner. Investigating the effect of drilling parameters on penetration rate in core drilling of deviated wells is important to optimize operations. In this regard, the rate of penetration is studied and simulated by preparing concrete samples for coring in a deviant way with laboratory devices, so that it reaches the most optimal state with the least amount of time, along with the necessary safety. In this research, cubic concrete samples with uniaxial compressive strength of 30 MPa and porosity of 31% have been used, and the effect of these parameters on the rate of penetration has been investigated by applying various weight on bit and angles of deviation. According to the experiments, the Direct effect of the weight on bit on the penetration rate until reaching the turning point and the optimal value was observed. Also, by increasing the extra weight on bit, it causes a change in the mechanism of the bit's performance in drilling and loses its tangential state and causes the small particles of the sample to be torn off, which reduces the life of the drill bit.