PETROLEUM RESEARCH
Year:2019 | Volume:29 | Issue:106 |Papers Count:13

It is essential to understand gas condensate reservoir behaviour correctly. A special way of meeting this requirement is taking the advantage of well testing analysis. The simultaneous presence of condensate and gas in a reservoir alters the gas relative permeability around a production well, which influences the well test responses. Moreover, another parameter which alters this behavior more is non-Darcy flow of fluid around the well. Furthermore, some factors like the rate of production and type of gas condensate reservoirs play a crucial role in condensate formation. These factors have important impacts on the formation of condensate. In other words, they add an additional skin factor caused by the formation of condensation around wells. The aim of this study is to consider the correlation between production rate and skin factor. Moreover, the method is using data obtained from a compositional reservoir model to investigate the transient behavior around the producing well and reinterpreting the results of the reservoir model during well test analysis. Finally, in this way, by creating different scenarios of production and build-up tests, the effects of downward and upward trends of the production rate on the condensate formation and its effect on the well-test data have been examined by us. Some weight functions for representing the production rate changes versus skin factor are developed as well.

treatment of effluent from Bandar Abbas oil refinery’ s wastewater treatment unit. The commercial type membranes used in this system were with two different pore sizes 0. 22 and 0. 45µ m, made of PTFE material with PP support. The cold flow was kept constant at 20 ° C, and the effect of some process factors on the amount of produced water flux such as feed temperature (hot flow), air gap, concentration of wastewater, and membrane pore size were studied as Feed temperatures were equal to 40, 50, 60, 70 and 80 ° C, air gaps were equal to 6 and 12 mm, feed concentrations were equal to 780, 2100, 3250, 4400 and 5200 μ s/cm. Also, the reduction of the amount of flux due to probable membrane fouling was investigated. Maximum produced flux was 16. 44 kg/(m2. h) which was obtained using a 0. 45 micron membrane, 6 mm air gap, and feed temperature of 80 ° C. Increasing the air gap from 6 to 12 mm decreased the flux about 34%, while reducing the electrical conductivity from 4400 to 780 μ s/cm, the amount of flux showed only 28% growth. Also, after about 30 hours of using the membrane without any cleaning system, the flux reduction was observed about 12%. Finally, according to the analysis of final purified water by membrane distillation method, the amount of TDS maximum 7. 8 mg/L, COD about 4 mg/L, and chloride less than 8 mg/L have been obtained; in addition, it has well been illustrated that the effluent of Bandar Abbas refinery’ s wastewater plant by using membrane distillation supplementation can be used at all different sections of industry.

Excess water production is a serious problem in oil industry. Chemical controlling methods such as injection of certain polymers are cheap and easy to handle. These polymers in the reservoir forms a gellant network which causes disproportionate permeability reduction (DPR). In fact, this method reduces both oil and water permeability; but reduction in water production would be much more than that for oil. Therefore, little water will be produced. Four experiments using core sample from a carbonate reservoir were carried out by employing distilled water as reference case and water with addition of different salts to represent formation water. The water permeability drastically reduced with addition of polymer in the reference case. However, addition of various ions to water especially ions with double positive charge decreased water and oil perm abilities in a rather similar way. Therefore, it is concluded that prior to applying polymer injection technologies into a reservoir, the formation water should be analyzed for double positive charges.

The purpose of this study was to investigate the effect of the Clay nanoparticles on the protective properties of the epoxy coating on carbon steel. The results of the electrochemical impedance spectroscopy (EIS) showed that the addition of this nanoparticle increased the corrosion resistance of the epoxy coating. The resistance of the coating containing 3% nanoclay after 1000 hours immersion in NaCl 3. 5 wt. % was about 3. 1 × 106 Ω . cm, indicating good resistance to the coating in the corrosive environment. Also, the results of electrochemical impedance showed that coating containing 3% nanoclay showed better resistance than coating containing 5% nanoclay. The results of the Scanning Kelvin Probe (SKP) showed that in nanoclay-containing samples after 2500 hours, the average potential of the surface gradually dropped from-345 mV to-700 mV, and the drop in surface potential in the presence of nanoclay was much less than in presence of nanoclay which indicates the positive effect of these nanoparticles on corrosion control. Moreover, Volta potential of varnish without a nanoparticle, reached a much lower level over the same period than a nanoclay sample of about 1500 mV. Finally, exfoliated nanoclays by reducing and prolonging the penetration path of electrolyte containing oxygen, water, and corrosive ions controlled the corrosion rate and postponed the time of penetration of the electrolyte.

In this study, a new approach based on the molecular structure of asphaltene is developed to model asphaltene precipitation by the cubic plus association equation of state (CPA EoS). The accuracy of the proposed approach has been proved by reproducing the experimental data of asphaltene precipitation in two different live oil samples. In this approach, five similar association sites were assigned to the asphaltene molecules. Self-association between the asphaltene molecules and cross-association between the asphaltene and heavy hydrocarbon component were considered. The critical pressure of the heavy component was tuned using a single experimental bubble point pressure of the oils. Results revealed that the approach is able to predict the bubble point curve of the oil samples with the average absolute relative error (AARE) of lower than 1. 54%. To model the asphaltene onset point, the cross-association energy between the asphaltene and the heavy component () was considered as the only tuning parameter of the model. It was assumed that the was temperature-dependent and three different dependency were considered. The results showed that the cross-association energy is inversely proportional to absolute temperature. The CPA EoS reproduces the asphaltene onset point of the oil samples with the AARE of lower than 5. 50%. At reservoir temperature, the asphaltene onset pressure for the two reservoir oil samples is 527 and 262 bar which is predicted by the CPA EoS as 502. 5 and 250. 4 bar respectively. As a conclusion, the proposed approach can not only predict the bubble point pressure but also accurately predict the general trend of asphaltene onset pressure with temperature.

In the drilling of oil and gas wells, confining pressure or the pressure at the well bottom is one of the effective factors affecting the rate of drilling and the amount of specific energy (the energy needed to remove a single volume of rock). In this operation, the rock cutting process is a combination of two modes of failures, i. e. brittle and ductile. Each of these failure modes has a different effect on the specific energy and structure of the crushed material, and thus on the rate of drilling. In this paper, the distinct element method is used to understand the relationship between rock fracture and confining pressure and its effect on the specific energy. For this purpose, a particle flow code is used that numerically simulates the mechanical behavior of the granular materials such as rocks. Based on the results obtained in condition of no confining pressure, the force applied to the cutter blade causes failure of the inter-granular connections in a single failure plane. But under confined pressure conditions, a different mechanism is taking place, and the difference in pressure created during the cutting action of PDC drill bits keep the crushed rock on each other and increase the mechanical specific energy of the rock cutters. Also, up to a pressure of about 26 MPa, with increasing tension, the specific energy has a relatively linear increase during the cutting action of the bits. But after this pressure due to the increased confining stresses and near-hydro-static conditions, the incremental increase in the mechanical specific energy decreases as the drilling depth increases.

A huge portion of natural gas reserves contains hydrogen sulfide in Iran. Therefore, the conversion of hydrogen sulfide to sulfur is important. In this paper, at first, titanium dioxide nanoparticles were synthesized with simple and inexpensive method of sol gel, and then nitrogen was doped on it, and their performance was investigated to direct hydrogen sulfide oxidation to elemental sulfur. The synthesized catalysts were characterized for the structure and morphology by XRD, FESEM, EDX, and BET analysis. Moreover, doping titanium dioxide nanoparticles with nitrogen has shown a better performance (more than 7% increases) for the removal of hydrogen sulfide than the undoped TiO2. The reason can be attributed to the synergistic effects of nitrogen and titanium dioxide nanoparticles, the increase of the specific surface area and the pore volume of N-TiO2, and also the existence of alkaline nitrogen groups in the titanium dioxide network.

One of the problems of oil and gas well drilling is significant instability in the well during drilling which leads to the break of surrounding formations of well during hydrocarbon production. This problem which is often named as sand production, is result of formation significant failure during hydrocarbon production, and its reason is the impact of tectonically stresses around the wells. This phenomenon poses some disadvantages such as erosion to surface and downhole facilities, and it leads to migration of fine particles toward oil and gas wells that occurs as a result of interactions in porous environment related to production factors. Moreover, drilling in a formation leads to accumulation of stresses around of borehole which it causes to failure. The purpose of this research is prediction of sand production problems in SDX-5 gas well of Shah Deniz gas field with using geomechanics and geodynamics information, petrophysical data, regional tectonics information, and sonic logs. Therefore, the STABView software was used to analyze geomechanical data. Finally, by importing required components of software such as formation parameters, rock mechanical properties and stress parameters and by interpreting the graphs obtained in STABView software, including the azimuth plot, inclination plot, polar plotes, and depth profiles, it was concluded that for compressional stress regime, drilling optimal azimuth was parallel to the direction of maximum horizontal stress, and drilling optimal inclination would be appropriate horizontally for all of the formations. Also, the optimal rate of hydrocarbon production flow and optimal collapse pressure for each of the formations, especially the formations related to the reservoir rock, was determined to prevent sand production.

The corrosion and scaling impose billions of dollars on the oil industry annually. Corrosion is one of the main reasons for the loss of metals in oil wells and production processes. Moreover, corrosion causes that the costs of maintaining wellhead and downhole equipment and its replacements and repairs increase. In addition, the cost of production increases due to corrosion. The purpose of this study is the determination of the corrosion rate and scaling deposition of wastewater of Rag-Safid desalination unit and tubing of the disposal well of this field using corrosion and scaling indexes until appropriate solutions for removal and minimization of corrosion and scaling in wastewater transmission tubes and disposal wells are provided. In this research, 10 indexes including Langelier, Ryznar, Puckorius, Aggressiveness index, Larsen index and Larson-Scold index, driving force index, Momentary excess index, saturation index, scaling index, Stiff and Davis saturation index (S and DSI), and the rate of corrosion rate (CRu) in terms of millimeters per year (mm/year) were measured by sampling parameters of wastewater of Rag-Safid desalting and formation water of this field and used for predicting scaling and corrosion rates. After considering the results of 10 corrosion indexes, scaling, and the rate of uniform corrosion (CRu), it is found out that the rate of corrosion of produced wastewater is high (in this study, the rate of CRu is equal to 67. 5 mm/year). In addition, carbonate calcium has precipitated at the wellhead and in transmission pipes of disposal well due to the existence of calcium (equal to 3926 mg/L) in the wastewater. Finally, Rag-Safid desalination unit forms due to the existence of (1) low amount of barium (equal to 5. 625 mg/L) in the produced wastewater and (2) precipitated carbonate calcium (equal to 3926 mg/L).

In this research, an air gap membrane distillation (AGMD) pilot was used for the tertiary treatment of effluent from Bandar Abbas oil refinery’ s wastewater treatment unit. The commercial type membranes used in this system were with two different pore sizes 0. 22 and 0. 45µ m, made of PTFE material with PP support. The cold flow was kept constant at 20 ° C, and the effect of some process factors on the amount of produced water flux such as feed temperature (hot flow), air gap, concentration of wastewater, and membrane pore size were studied as Feed temperatures were equal to 40, 50, 60, 70 and 80 ° C, air gaps were equal to 6 and 12 mm, feed concentrations were equal to 780, 2100, 3250, 4400 and 5200 μ s/cm. Also, the reduction of the amount of flux due to probable membrane fouling was investigated. Maximum produced flux was 16. 44 kg/(m2. h) which was obtained using a 0. 45 micron membrane, 6 mm air gap, and feed temperature of 80 ° C. Increasing the air gap from 6 to 12 mm decreased the flux about 34%, while reducing the electrical conductivity from 4400 to 780 μ s/cm, the amount of flux showed only 28% growth. Also, after about 30 hours of using the membrane without any cleaning system, the flux reduction was observed about 12%. Finally, according to the analysis of final purified water by membrane distillation method, the amount of TDS maximum 7. 8 mg/L, COD about 4 mg/L, and chloride less than 8 mg/L have been obtained; in addition, it has well been illustrated that the effluent of Bandar Abbas refinery’ s wastewater plant by using membrane distillation supplementation can be used at all different sections of industry.

The objective of this research is to model and optimize the effective operation parameters of catalytic oxidation of carbon monoxide (CO) using 15 wt. % cobalt-cerium oxide with weight ratio of cobalt to cerium=1. 5 supported by multiwalled carbon nanotubes by response surface method. Therefore, 30 sets of experiments were employed to evaluate the influence of the four independent variables including temperature, gas hourly space velocity, O2 concentration, and CO concentration in 5 levels (-2,-1, 0, +1, +2). The experimental design results showed that there is a quadratic model as a functional relationship between CO conversion (response variable) and four independent variables. The data from response surface method explored that CO conversion was highly affected by temperature and O2 concentration. The optimum amounts of the effective parameters for 100% conversion of CO were followed as: temperature= 200 ° C, CO concentration =780 ppm, O2 concentration =5. 25 vol. %, and Gas hourly space velocity= 10000 h-1. Analysis of variance with R2 value of 0. 9994 showed a satisfactory correlation between the experimental data and predicted values for conversion of carbon monoxide.

The performance of M/ZnLaAlO4 and M/γ – Al2O3 catalysts (M=Cu, Cu– Ni) in methanol reforming process in the temperature range of 200-350 oC, methanol feed GHSV of 11500 h-1, and atmospheric pressure in a fixed bed quartz reactor has been investigated in this work. Surface area, morphology, and crystal structure of the synthetic catalysts were studied using BET, FESEM, FIR, XRD, and TPR analyses for better assessment of the catalysts. The results have shown that the spinel based M/ZnLaAlO4 catalyst possesses high yield, very high catalytic activity, low reduction temperature, and large pore sizes, giving a higher percentage of loading and better distribution of the active metal. The new support catalyst selectivity is less carbon monoxide. Finally, the bimetallic catalyst, nickel leads to better dispersion of copper particles and increases the activity but also high selectivity to the carbon monoxide.