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.

Hole cleaning is one of the most important aspects of extractive DRILLING operations. When drill cuttings combine with DRILLING FLUIDs, cutting bed gel is created, which becomes extremely challenging to remove while DRILLING. One of the functions of DRILLING FLUID when the flow is static is to maintain the drill bits' suspension. However, the settling of drill bits makes this nearly impossible. In this paper, the influence of FLUID viscosity on hole cleaning performance was critically studied through a series of laboratory experiments. The effects of different viscosity levels on hole cleaning were investigated. This paper evaluated the use of lecithin and carboxymethyl hydroxyethyl cellulose (CMHEC) as a viscosifier and FLUID loss agent in oil-based DRILLING FLUID. The rheological properties of the formulated DRILLING FLUIDs were determined at various temperatures according to the API 13B-2 specifications in order to identify the most suitable mud type for high-temperature DRILLING operations. From this study, it was discovered that Formulation B has the best rheology, with a plastic viscosity (PV) of 12, 7, and 7 cP at 30, 40, and 50 °C, respectively, while its yield point (YP) was found to be 30, 24, and 16, respectively. These values were compared with the generic oil-based formulation (A), which had a plastic viscosity (VP) of 43, 39, and 22 cP at 30, 40, and 50 °C, respectively, while its yield point (YP) was found to be 38, 20, and 26, respectively. The findings show that formulation B has a significant resistance to high temperatures, which means that it can be applied to DRILLING operations in reservoirs with high temperatures. It is more environmentally friendly. Furthermore, this paper explores the implications of the results in terms of the efficiency of hole cleaning and the DRILLING process relative to the viscosity of oil-based DRILLING FLUID. This paper concludes by providing suggestions for improving DRILLING efficiency through the selection of an appropriate DRILLING FLUID viscosity.

Background: Biodegradation of starch used in DRILLING FLUID by many microorganisms, results in reduction of starch concentration in the FLUID, which leads to FLUID efficiency downfall. The aim of present study was to identifythe major starch degrading bacteria in the DRILLING FLUID and manner of controling the growth and activity of these organisms.Methods: Bacteria present in back up DRILLING FLUID, were isolated and their amylase activity was studied by starch hydrolysis test. The strain with the most ability of starch hydrolysis in all three temperatures (37, 45 and 55oC) was selected as the superior strain and was identified by 16Sr RNA. Also growth curve of superior strain was plotted.Results: 54 bacterial strains include 26 Gram-positive Bacillus, 22 Gram-negative Bacillus and 6 Gram-positive Cocci were isolated. 18 strains from 26 Gram-positive Bacillus were spore forming bacteria. Three strains had growth in all three temperatures (37, 45 and 55oC) and showed significant amylase activity. Bacteria with the most mean of inhibition zone were selected as superior strains. The results of the 16Sr RNA analysis showed 99.8% similarity of superior strain to Bacillus licheniformis. The bacterium was in logarithmic phase at 8-48 hour after inoculation.Conclusion: Spore forming Gram-positive Bacillus belonging to Bacillus Genus like Bacillus licheniformis isolated in this study was the most active bacteria of degrading in well special conditions. Identification of degradation factors with the aim of selecting a suitable biocide is important to prevent the biodegradation.

A successful DRILLING operation depends strongly on a useful DRILLING FLUID system. Using nanoparticles (NP)s to formulate intelligent DRILLING FLUIDs gives them a wide range of optimal properties under different operating conditions and resolves any operational problems. In this study, in order to provide an effective solution for improving the rheological and high pressure/high temperature (HPHT) filtration properties of the oilbased DRILLING FLUID (OBDF), copper oxide (CuO) NPs were synthesized with dandelion morphology. CuO dandelions were characterized by using XRD, FTIR, SEM, and zeta potential measurements. A long time stabilized nanoFLUID (NF) was prepared and evaluated. The OBDF samples consisting of various amounts of NF ranging from 1 to 11% (V/V) were prepared. Then, the FLUID loss and rheological properties of OBDF were examined. The results showed that the OBDF containing 7% (V/V) NF was appropriate to improve the rheological properties such as yield point (YP), apparent viscosity (AV), and gel strength (GS). In addition, the minimum HPHT filtration value of 2 ml was acquired for the DRILLING FLUID containing 9% (V/V) NF. In conclusion, CuO NPs demonstrated a positive effect on the performance of the OBDF system.

In this study, using the results of performed shale formation Characterizatins and the history of DRILLING in Iranian oil fields, an environmentally friendly water based DRILLING FLUID is designed to replace the oil based DRILLING FLUIDs. This DRILLING FLUID has desirable properties in DRILLING water sensitive formations. New DRILLING FLUID additives including shale inhibitors, new polymers and sized solid particles have been used to prepare this new DRILLING FLUID. The most important properties of this new DRILLING FLUID are controlling the mud filtrate and pressure invasion to the formation, clay mineral alteration and activity reduction, improvement of the integrity of DRILLING cuttings, reduction in formation damage, stability at high temperatures, stability in acidity changes and the compatibility by DRILLING FLUIDs dilution during DRILLING operation. The lubricity and shale cuttings recovery of this new DRILLING FLUID are better than those of other similar water based DRILLING FLUIDs. Replacing this DRILLING FLUID by oil based DRILLING FLUIDs in DRILLING industry will be a great means to protect the environment and DRILLING personnel in addition to being economically advantageous.

Hydrogen sulfide is a very dangerous, toxic and corrosive gas. It can diffuse into DRILLING FLUID from formations during DRILLING of gas and oil wells. Hydrogen sulfide should be removed from this FLUID to reduce the environmental pollution, protect the health of DRILLING workers and prevent corrosion of pipelines and equipments. In this research nano zinc oxide with 14-25 nm particle size and 44-56 m2/g specific surface area was synthesized by spray pyrolysis method. The synthesized nanoparticles were used to remove hydrogen sulfide from water based DRILLING FLUID. The efficiency of these nanoparticles in the removal of hydrogen sulfide from DRILLING mud were evaluated and compared with that of bulk zinc oxide. The obtained results show that synthesized zinc oxide nanoparticles are completely able to remove hydrogen sulfide from water based DRILLING mud in just 15 min., whereas bulk zinc oxide is able to remove 2.5% of hydrogen sulfide in as long as 90 min. under the same operating conditions.

An improved model of mud dispersion has been introduced in this work. The advantages of this model consist of a new analytical correlation for dispersivity by using resistivity log data and using a new aspect of capacitance dispersion model. Mathematical formulations were expressed, solved by numerical model taking advantage of actual log and formation data. Achieved results yielded reasonable values and trends which can be used to predict the DRILLING FLUID concentration near wellbore region and interpret the well log data. In comparison with the previous models (Civan and Engler, 1994; Donaldson and Chernoglazov, 1987), this model uses more reasonable data and assumptions making it closer to real conditions.