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Well Deviation Problem: A Case Study in an Iranian Gas Well Drilling
Get PDF Unexpected well deviations can bring the drilling projects lots of financial and technical damages. As a result, investigation of the Bottom Hole Assembly (BHA) tendency and prediction of the probable mechanical behavior of the drilling string, especially when a new configuration is running in the hole, is critical to prevent unexpected failures. In this paper, a drilling project in an Iranian gas field which ended in a catastrophic well trajectory is going to be studied in more detail. Here, we try to answer three main questions. The reasons for the unusual well trajectory and the possibility of predicting this behavior is the first issue. The second question is about the signs of this failure during the operation and the ways that we could detect it earlier. In the third question, the alternative plans that can prevent this problem are examined by studying different BHA configuration and drilling parameters. The major sources of our information are the daily drilling reports, well log data, related published articles, and numerical simulations in WELLPLANTM software of Landmark package. According to the simulation results, BHA design is one of the most effective factors in this case study and its effect could be predicted using BHA tendency analysis before starting the drilling operation. During drilling of this well, some anomalies have been observed in drill string mechanical parameters such as hook load, rotation torque and up and down drags. Simulation of torque and drag charts for some probable well trajectories shows completely different trends for the expected well trajectory and the actual one. The observed data during the drilling operation are similar to the ones simulated for a highly deviated well and are completely unlike the trend of the near-vertical well path. Hence, it was possible to detect the wrong situation if we had simulated the mechanical behavior of the drill string and compare it with the actual observations during the operation. Finally, examination of various BHAs reveals that using an in-gauge stabilizer 10 meters above the bit instead of the one that is 20 meters above the bit could provide better well path control. It is completely obvious from the different build and walk rates which resulted in about 19 different BHA configurations. Moreover, the suggested BHAs demonstrate a good tolerance in case of changing WOB in the desired range. In the end, besides from being careful and alert during the drilling operation, the application of credible drilling simulators is strongly recommended in order to prevent unforeseen situations and also to be prepared if some happen
Physically Activated Agricultural Waste Biochars for Production of Pollutant Adsorbents
Get PDFVarious nut residues from agricultural production were investigated for their potential to be used as active carbons. Raw materials were pyrolyzed in a fixed bed unit and subsequently gasified by steam or carbon dioxide at different temperatures and duration of heat treatment. Biochars were characterized by physical and chemical analyses with respect to temperature and gasifying agents. Organic and mineral matter, elemental composition, structural characteristics, and surface functional groups were determined. Activation by steam presented a higher reactivity than carbon dioxide, reduced the yield of biochars, consumed more oxygen organic functional groups, favoured pore enlargement at high temperature, and increased the specific surface area (maximum 1257 m2/g) of pyrolyzed materials by 1.4 to 3.8 fold. Activation by carbon dioxide disrupted the hydrogen char structure, favoured microporosity, and increased the specific surface area (maximum 637 m2/g) of pyrolyzed materials by 1.8 to 3 fold. Gasified biochars at a high temperature were highly carbonized and exhibited aromatic structures, especially under steam activation
Different Active Sites of LaCoO3 and LaMnO3 for CH4 Oxidation by Regulation of Precursor’s Ion Concentration
Get PDF Pure LaCoO3 and LaMnO3 were synthesized under different ion concentrations of precursors and the difference of active sites for CH4 oxidation between them was found. As the ion concentration of precursors increased, the two kind of perovskite crystals grew larger along with agglomerate. Meanwhile, LaCoO3 and LaMnO3 prepared by high ion concentrations of precursors enriched more surface Co3+ or Mn4+. The catalytic activity of the catalysts was tested in the oxidation reaction of methane under fuel-lean condition, results showed that LC-1.0 and LM-2.0 had the optimal activity and the light-off temperatures were 492°C and 486°C, respectively. Combining the physical and chemical characterization, the LaCoO3 and LaMnO3 possess different active sites for the methane catalytic reaction, and the conclusion was further verified by the DFT simulation. For LaCoO3, the surface lattice oxygen is the main active site, while for LaMnO3, the reaction is facilitated by the high-valent manganese
On Some Aspects of Generalized Extended Yule Distribution: Properties and Applications
Get PDFMartinez-Rodriguez (Comp. Statist. Dat. Anal., 2011) studied an extended version of the Yule distribution, namely “the extended Yule distribution (EYD)” which they obtained as a mixture of geometric distribution and generalized beta distribution. Through the present paper, we propose a generalized version of the EYD and named it “the generalized extended Yule distribution (GEYD)”. Several statistical properties of the distribution are obtained, including probability generating function (p.g.f), moments, recursion formulae etc. The maximum likelihood estimation of the parameters of the GEYD is discussed and fitted to two real-life data sets for illustrating its usefulness compared to the existing models. Further, the generalized likelihood ratio test procedure is considered for testing the significance of the parameters of the GEYD
Volume Fracturing Technology Application in the World's Largest Conglomerate Oil Field, Northwest of China
Get PDF One billion-ton super large oil field of Mahu is the largest oil and gas exploration achievement in China in recent years and has become the most realistic replacement area for increasing reserves and production in China as the world's largest conglomerate oil field till now. According to the complex reservoir-forming conditions in Mahu Sag, poor reservoir property, strong heterogeneity, and large sand body span, hydraulic fracturing in this area was facing serious challenges in fracture initiation and proppant placement. It has deepened the concept of volume fracturing technology and improved the effect of reconstruction; advanced chemicals to optimize replacement and reduce costs; tackled key perforation bridge plug with production technology to improve the level of operation according to 5 year’s stimulation experiences. The volume fracturing series technologies have been widely applied in 11 blocks and 97 wells in Mahu, including most of the exploration, evaluation, and development areas. For the tight conglomerate oil reservoir of Mahu, the fracturing and producing effects accompanied by economic development have been realized and effectively promoted, thus the average cumulative production increased by 37.5% per year
Evaluation of Mine Water Quality Based on Bayesian Theory MODEL of AHP-EWM Combined Weighting Method
Get PDFIn view of the fuzziness and randomness of groundwater quality evaluation and the rationality and scientificityof the weight in the evaluation process, in order to establish an objective, scientific and convenient mine waterenvironment evaluation system and improve the accuracy of the evaluation results, AHP and EWM weight method arecombined to obtain the weight value, which is coupled with Bayesian water quality evaluation model. In this paper, sevenwater quality evaluation factors and ten groups of water samples are selected to analyze the application of mine water inShengquan coal mine, Shandong Province. At the same time, the single factor evaluation method, equal weightBayesian model and fuzzy comprehensive evaluation method are used to compare with the evaluation results to verifythe accuracy of the evaluation results of the model. The results show that the water quality evaluation model ofcombined weighted Bayesian model is reasonable for mine water quality evaluation, which not only distinguishes thedifference of each evaluation factor's contribution to water quality, but also makes a more accurate evaluation of waterquality, and the calculation process is simple, which avoids the complexity of multiple indicators of traditional methods,and provides a scientific basis for comprehensive utilization of mine water in mining area, so the evaluation method ispractical.
 
Case Study of Petrophysical Evaluation Utilizing Well Logs Data with Optimization of Reservoir Cut-off Parameters
Get PDFPetrophysical evaluation of well log data is essential for the exploration and evaluation of hydrocarbon-bearing formations. Moreover, there are no standard criteria to implement cut-offs on petrophysical properties as a direction for economic decisions. In the present work, a petrophysical evaluation of well logging data from four wells in a mature oil field is performed to identify formation quality as a potential for hosting mature hydrocarbons reservoirs. Full consideration of cut-off values was taken into account. The cut-offs were estimated from well-recognized petrophysical relationships for permeability as a function of porosity, water saturation, and shale content. Results verification and calibration were also made based on laboratory measurements of petrophysical properties obtained from available core plugs in order to minimize uncertainty. Lithology analysis and characteristics revealed that the target formation is mainly sand and shale sequences. Results from well logs were in agreement with results obtained from core data. Formation effective porosity varies from 16 to 26% in all wells. A wide range of variations is observed in water saturation ranging from 28 to 57% and permeability ranging from 20 to 3300 mD. This is in good agreement with other measurements and well log analysis that show the mature formation remains to be a good hydrocarbon reservoir with significant potential
Numerical Simulation of High Temperature PEM Fuel Cell Performance under Different Key Operating and Design Parameters
Get PDFThe negative environmental impacts of internal combustion engines have changed the interest of scientists towards fuel cell engines. Using Proton Exchange Membrane (PEM) fuel cell operating under higher temperature solves some of the well-known low temperature problems. In this study, a numerical simulation has been carried out using a three-dimensional model in COMSOL to evaluate the performance of high temperature PEM (HT-PEM) fuel cell under different conditions. The obtained polarization curve for selected voltage was compared with published experimental data, and it shows a good agreement. The simulation results in terms of reactants (hydrogen and oxygen) concentrations and water production on the anode and cathode sides is presented. The influences of some key parameters on HT-PEM fuel cell performance were investigated. It was found that as the temperature and pressure increase, the performance of the HT-PEM fuel cell improves. The enhanced reaction rate and a better supply of reactants were observed to have a positive influence on HT-PEM fuel cell performance. Additionally, the results show that considering a higher permeation rate on the gas diffusion layer can enhance the performance of the fuel cell. This work provides a guideline to design and optimize a HT-PEM fuel cell with a better capability
A Review of the Global Change Research on the Tibetan Plateau: From Field Observation to Manipulative Experiments
Get PDF Global temperature increases and precipitation changes are both expected to alter alpine ecosystem structure and processes. In this paper, we reviewed the recent climate changes observed and the global change researches on the Tibetan Plateau. Firstly, we found that the mean annual temperature and precipitation (data from 75 meteorological stations, where all daily precipitation data are available) have increased since 1971, there were 0.5˚C and 0.7˚C per decade increase in annual and winter temperature, respectively, on Tibetan Plateau, and changes in precipitation were found both less spatially and temporally consistent. Secondly, we reviewed the climate change researches on the Tibetan Plateau published between 2000 and 2019 mainly focused on plant growth and ecosystem carbon balance which including plant phenology, plant productivity, plant diversity, exchanges in ecosystem carbon and soil organic carbon. Findings and insights from these studies have been very useful to understand how the alpine ecosystem processes respond to climate change. However, the effects of temperature increase on plant growth and ecosystem carbon balance are differ depending on the study sites and warming methods and periods, and the effects of precipitation changes are sparse
Optical Soliton Solutions of Fokas-Lenells Equation via (m + 1/G')- Expansion Method
Get PDFIn this research paper, we investigate some novel soliton solutions to the perturbed Fokas-Lenells equation by using the (m + 1/G') expansion method. Some new solutions are obtained and they are plotted in two and three dimensions. This technique appears as a suitable, applicable, and efficient method to search for the exact solutions of nonlinear partial differential equations in a wide range. All gained optical soliton solutions are substituted into the FokasLenells equation and they verify it. The constraint conditions are also given