South Pars Research Articles

Spectral gamma‐ray logs and palaeoclimate change? Permian–Triassic, Persian Gulf

Spectral gamma ray (SGR) logs are used as stratigraphic tools in correlation, sequence stratigraphy and most recently, in clastic successions as a proxy for changes in hinterland palaeoweathering. In this study we analyse the spectral gamma ray signal recorded in two boreholes that penetrated the carbonate and evaporate‐dominated Permian–Triassic boundary (PTB) in the South Pars Gasfield (offshore Iran, Persian Gulf) in an attempt to analyse palaeoenvironmental changes from the upper Permian (Upper Dalan Formation) and lower Triassic (Lower Kangan Formation). The results are compared to lithological changes, total organic carbon (TOC) contents and published stable isotope (δ18O,δ13C) results. This work is the first to consider palaeoclimatic effects on SGR logs from a carbonate/evaporate succession. While Th/U ratios compare well to isotope data (and thus a change to less arid hinterland climates from the Late Permian to the Early Triassic), Th/K ratios do not, suggesting a control not related to hinterland weathering. Furthermore, elevated Th/U ratios in the Early Triassic could reflect a global drawdown in U, rather than a more humid episode in the sediment hinterlands, with coincident changes in TOC. Previous work that used spectral gamma ray data in siliciclastic successions as a palaeoclimate proxy may not apply in carbonate/evaporate sedimentary rocks. Copyright © 2014 John Wiley & Sons, Ltd.

Power Consumption Minimization of Khormoj Compressor Station

Arguably, the natural gas transmission pipeline infrastructure in Iran represents one of the largest and most complex mechanical systems in the world. The optimization of large gas trunk lines known as IGAT results in reduced fuel consumption or higher capability and improves pipeline operation. In the current study, a single-objective optimization was conducted for Khormoj compressor station on the Iranian gas trunk line V (IGAT5). The system consists of over 504 kilometers of 56-inch pipeline from South Pars to Aghajari. This system passes through a tortuous terrain with changes in elevation which makes the optimization process even more challenging. Genetic algorithm (GA) was used in this optimization along with detailed models of the performance characteristics of compressors. The results show that in stations having the same compressor in parallel the minimum power (energy) consumption is reached when split flow in all the compressors is the same.

Field experience and evaluation of the South Pars sea line pigging, based on dynamic simulations

Multi-phase flow is experienced in many instances of the oil and gas industry. There is multi-phase flow in the sea lines, transferring the production from the South Pars offshore platforms to the receiving onshore facilities. By pigging at frequent intervals, liquid inventory buildup in a sea pipeline and the maximum slug size can be reduced. Uncontrolled speed of a pig can cause to large liquid slugging formation and bursting of pipeline due to pig stuck. In June 2008 the slug catcher levels increased unexpectedly to 100–105%. The main objective of this study is composed of calculation for liquid holdup, pig velocity, amount of slug during pigging operation and the influence of the production flow rate during the pigging of South Pars sea lines that is located in south of Iran. Besides the slug catcher liquid level, some parameters such as liquid bottle level were measured during pigging time process. The comparison between the actual and simulated sea line glycol holdup, travel time for the pig, sea line inlet pressure and the liquid slug volume has been done in this work. The difference between the actual and simulated travel time for the pig was 0.7 and 1.3 h for 600 and 300 million standard cubic feet per day (MMSCFD) of the gas flow rate. The absolute average relative errors of condensate and water slug volume are 5.6% and 9.1% respectively, which are very satisfactory. The results showed that the optimum gas flow should be around 500 MMSCFD to handle the slug volume and running the pigs is most effective at a near constant speed.

Committee neural network model for rock permeability prediction

Quantitative formulation between conventional well log data and rock permeability, undoubtedly the most critical parameter of hydrocarbon reservoir, could be a potent tool for solving problems associated with almost all tasks involved in petroleum engineering. The present study proposes a novel approach in charge of the quest for high-accuracy method of permeability prediction. At the first stage, overlapping of conventional well log data (inputs) was eliminated by means of principal component analysis (PCA). Subsequently, rock permeability was predicted from extracted PCs using multi-layer perceptron (MLP), radial basis function (RBF), and generalized regression neural network (GRNN). Eventually, a committee neural network (CNN) was constructed by virtue of genetic algorithm (GA) to enhance the precision of ultimate permeability prediction. The values of rock permeability, derived from the MPL, RBF, and GRNN models, were used as inputs of CNN. The proposed CNN combines results of different ANNs to reap beneficial advantages of all models and consequently producing more accurate estimations. The GA, embedded in the structure of the CNN assigns a weight factor to each ANN which shows relative involvement of each ANN in overall prediction of rock permeability from PCs of conventional well logs. The proposed methodology was applied in Kangan and Dalan Formations, which are the major carbonate reservoir rocks of South Pars Gas Field-Iran. A group of 350 data points was used to establish the CNN model, and a group of 245 data points was employed to assess the reliability of constructed CNN model. Results showed that the CNN method performed better than individual intelligent systems performing alone.

Assessing and optimization of pipeline system performance using intelligent systems

The fuel consumption minimization of a pipeline system including boosting units has been investigated in this paper. Virial equation of state has been used to study steady state non-isothermal flow of natural gas. Due to the complexity of mentioned equations and requirement time to study the different operating states, intelligent systems including Artificial Neural Network (ANN), Adaptive Neuro-Fuzzy inference System (ANFIS), and Fuzzy Inference System (FIS) are applied to predict and optimize the pipeline system. As a case study, IGAT 5 pipeline with four compressor stations is chosen to be explored which transports the natural gas from Asalouyeh (South Pars Energy Zone-IRAN) for oil well injection purposes. The results have shown that ANN is slightly more accurate than the other two predictive methods. Therefore ANN results are introduced to Genetic Algorithm (GA) to determine the optimum speed of each compressor and their compression ratio.

Designing a Model for Operational Resistance Strategy , New Approach to Achieve National Self-Sufficiency : Case Study : South Pars Gas Company

Designing a Model for Operational Resistance Strategy , New Approach to Achieve National Self-Sufficiency : Case Study : South Pars Gas Company

Exploitation of Shared Hydrocarbon Resources: A Game Theory Analysis

The North Field/South Pars gas condensate field is the world’s largest gas field with an estimated 1800 trillion cubic feet (tcf) of gas in place and 50 billion barrels of gas condensate. The estimated recoverable reserves are 1,260 tcf, accounting for 19% of the world’s recoverable gas reserves [1]. This field is shared by Qatar and Iran with an estimated 3:1 share of the reserves respectively (divided by the maritime border). These estimates are based on static volumetric estimates. However, the ultimate recoverable reserves are dependent on the development schedule implemented by each country. In 2005, Qatar’s government announced a moratorium on further development projects on the north field in 2005 that is expected to extend till at least 2015 after higher than expected pressure depletion [2, 3]. Meanwhile, the Iranian government has called for and implemented rapid development of their share of the field, the South Pars. This example showcases the interesting nature of the shared resource development task to be analyzed using the principles of game theory. In general terms, since the ultimate recovery of each player (resource owner) depends on their individual production schedule, the situation presents a ‘first-mover advantage’ scenario. It is possible for either player to produce their share of the resource as soon as possible leading to rapid pressure depletion, it would not be illegal to do so. However, the depleted pressure would make development of the other player’s share of the resource uneconomical. The goal of the proposed paper is to study possible strategies and outcomes for exploitation of such shared hydrocarbon resources. The players involved may include resource owners such as land owners or countries and the strategies involved can be cooperative or non-cooperative. In the case of cooperative production strategies, also known as unitization, methods for profit sharing are also discussed.

3D BASIN MODELLING IN THE CENTRAL PERSIAN GULF, OFFSHORE IRAN

In the Central Persian Gulf, super‐giant natural gas accumulations in Permo‐Triassic reservoirs are assumed to be derived from “hot shale” source rocks in the lower Llandoverian (base‐Silurian) Sarchahan Formation, whereas oil in Mesozoic reservoirs is derived from Mesozoic source rocks. A 3D basin model has been established for a study area located in the Iranian part of the Central Persian Gulf in order to help understand the petroleum systems there. Sensitivity analyses considered different heat flow scenarios, and differences in the timing of Cenozoic uplift and erosion. For the Palaeozoic petroleum system, different thicknesses and distributions of the Silurian source rocks were considered.From current temperature profiles measured in five wells, present‐day heat flow was found to be in the order of 65 mW/m2, while palaeo heat flow was probably between 60 and 68 mW/m2 during Cenozoic maximum burial. For Llandoverian source rocks, oil and gas generation commenced during Jurassic and Late Cretaceous time respectively, and gas generation continued until the Neogene. Sensitivity analyses show that different assumptions on the timing of Cenozoic erosion do not have significant effects on the calculated timing of hydrocarbon generation or on the volume of generated hydrocarbons. As expected however, different heat flow scenarios (e.g. time‐constant heat flow of 65 mW/m2 in the entire study area) had a significant influence.With an assumed 50 m thick Sarchahan “hot shale” succession developed uniformly in the study area (8 % TOC; 470 mg HC / g TOC HI), the model calculated gas accumulations which are of the same order of magnitude as those which have been discovered in this region (e.g. South Pars, Golshan and Balal fields). By contrast, scenarios with thinner “hot shales” and models without the Sarchahan Formation along the Qatar‐South Fars Arch do not predict the known accumulations. These scenarios suggest that prolific Silurian source rocks must be present on both sides of the South Pars / North Dome field, or that lateral gas migration from the south may have supplied the Permo‐Triassic reservoirs.This study shows that the Jurassic (mainly Hanifa / Tuwaiq Mountain Formation) and Cretaceous (Shilaif Formation) source units are not sufficiently mature in the study area to have generated significant volumes of oil. This result supports previous suggestions which envisaged lateral migration from the south of the oil present in Mesozoic reservoirs in the study area.

Survey the Outbreak of Giardiasis Among Food Supply and Distribution Staff of South Pars Economic Zone Petrochemicals

Survey the Outbreak of Giardiasis Among Food Supply and Distribution Staff of South Pars Economic Zone Petrochemicals

The Optimization of Effective Factors on Mercaptan Extraction by Alkaline Solution

General LPG sweetening method used in Iran's South Pars Gas Complex is Sulfrex liquid-liquid extraction and caustic regeneration processes which uses caustic as alkaline solution to extract mercaptans from propane and butane cuts and also uses LCPS 30 as catalyst to regenerate of exhaust caustic. The authors focused on the extraction section process. Also effect of the main operating variables on mercaptans extraction, including extraction temperature, concentration, flow rate, and amount of caustic as alkaline solution were studied and at the end, according to laboratory results, operational process parameters were optimized and tuned.

Environmental and sequence stratigraphic implications of anhydrite textures: A case from the Lower Triassic of the Central Persian Gulf

The Lower Triassic Kangan Formation in the Persian Gulf (South Pars Gas Field) and its adjacent areas are composed of carbonate–evaporite sequences. These sediments were deposited in a shallow marine homoclinal ramp. Study of the anhydrite-bearing intervals shows various structures and textures. The anhydrite structures are mainly bedded, massive, chicken-wire and nodular type and the main textures are felted, sparse crystal, needle shape, lath shape, equant and fibrous. Pervasive and poikilotopic cement together with replacement and porphyroblastic gypsum are accounted as the most common diagenetic features in anhydrite. Evaluation of anhydrite occurrences and features support both primary and secondary formations. The nodular to chicken-wire anhydrite formed under synsedimentary sabkha conditions, whereas anhydrite cements occurred during the late stages of diagenesis (shallow burial stage). Massive to bedded anhydrite could have been formed under subaqueous conditions or originated by coalescing and continued growth of anhydrite nodules in the sabkha zone. Anhydrite fabrics impose a significant control on the reservoir quality of the Kangan carbonates at the South Pars Gas Field. Thick massive and bedded anhydrite could have been formed as an intraformational seals and anhydrite cements occluded pore spaces and reduced the poroperm values. The sequence stratigraphic analysis revealed two depositional sequences in the studied intervals, which are composed of TST and HST. Investigation of anhydrite throughout depositional sequences indicates a change in the content and style of anhydrite texture. Anhydrite content (volume) decreases upward through transgressive system tract (sea-level rise) whereas, it enhances during highstand system tract (sea-level fall). Pervasive and poikilotopic anhydrite cements together with replacement by anhydrite are prevalent features during transgressive and early highstand system tract. At the late HST, with a progradational stacking pattern, anhydrite value increases and felted, radial, equant, crystalline and mosaic texture are the most common anhydrite fabrics. Sequence boundaries that indicate maximum sea level fall and exposure of successions are marked by the broad anhydrite deposits with massive to bedded and chicken-wire structures and various textures that located in late HST package. There is an unambiguous relationship between the microfacies associations, the evaporite textures, and the sea-level fluctuations. This relationship could lead to a predictable pattern that can be of use as a general guide for the sequence stratigraphic interpretations in the area.

Understanding the fracture role on hydrocarbon accumulation and distribution using seismic data: A case study on a carbonate reservoir from Iran

Abstract The South Pars, the largest gas field in the world, is located in the Persian Gulf. Structurally, the field is part of the Qatar–South Pars arch which is a regional anticline considered as a basement-cored structure with long lasting passive folding induced by salt withdrawal. The gas-bearing reservoir belongs to Kangan and Dalan formations dominated by carbonate rocks. The fracture role is still unknown in gas accumulation and distribution in this reservoir. In this paper, the Scattering Index (SI) and the semblance methods based on scattered waves and diffraction signal studies, respectively, were used to delineate the fracture locations. To find the relation between fractures and gas distribution, desired facies containing the gas, were defined and predicted using a method based on Bayesian facies estimation. The analysis and combination of these results suggest that preference of fractures and/or fractured zones are negligible (about 1% of the total volume studied in this paper) and, therefore, it is hard to conceive that they play an important role in this reservoir. Moreover, fractures have no considerable role in gas distribution (less than 30%). It can be concluded from this study that sedimentary processes such as digenetic, primary porosities and secondary porosities are responsible for the gas accumulation and distribution in this reservoir.

Prioritization of Effective Risk Factors on Oil Industry Construction Projects (By PMBOK Standard Approach)

This study is an applied, analytic-descriptive research in terms of nature. It is thus an analysis in which a sample has been applied for data collection and it is descriptive since its variables are assessed and reported as they are in reality. This study seeks to identify effective risks existing in construction industry specifically in the national macro projects such as oil industry projects through utilizing Project Management Body of Knowledge (PMBOK) model and to estimate the relative impact of each risk on the projects. It aims at prioritizing the effective risk factors on the construction projects (a case study of National Iranian Oil Company). Thus NIOC construction projects, consulting engineers companies and contractor companies in construction projects of oil industry have been selected as the statistical universe to identify and prioritize the risks. Due to the focus of oil industry construction projects on South Pars Special Economic Zone, under planning, implementation or completion phases and with regard to the phases' expansion in terms of number and volume of activities and also strategic features and confidentiality of information, three phases out of 28 ones have been case-studied. It is generally concluded in this study that with respect to the country significant strategic, geopolitical, geographical, economic and military position in the world, it is a matter of great magnitude to regard the risks identification and management as one of the important areas in the project management and to consider it as a national and comprehensive plan when designing and ratifying industrial projects of the country.

Providing a Model for Identification and Evaluation of Risks in Construction Projects

The present study is a kind of practical, analytical and descriptive in nature. Being analytical is due to collection of information by sampling and descriptive because the variables are measured as they are in real life. In this study by gathering evidences on existing effective risks in oil industry we aim to identify risk limits and present a more precise definition of risks of low, medium and high risks borders. Because of centralization of construction projects of petroleum industry in special economic zone of South Pars, planning, implementation and completion phases based on phases broadness regarding number and size of activities and separate strategic characteristics, 3 out of 28 phases were undertaken sample case study. It is concluded in general that using quantitative and numerical methods in determination of high and low risks approve more precise results. Additionally, carrying numerical tests out requires documentation within study based on identification of potential risks, risk record (earlier and similar) as well as estimation of incidence of risk probability. Though frequency of risk may be less damaging, as reproducibility rule suggests it can be highly risky.

Survey affects of effective factors on contracts for development of south pars gas field

Exploration and extraction contracts are the main tool for using foreign new technologies for development of offshore oil and gas resources. Some factors such as risk aversion of owner country and foreign company, oil and gas price and asymmetric information have effects on value of contracts. These factors are so important in developing of contracts for extraction from offshore resources as South Pars Filed in Iran, exactly in some contracts such as buyback contracts.

Investigation of heat stress in workplace for different work groups according to ISO 7243 standard in Mehr Petrochemical Complex, Assaluyeh, Iran

Heat stress is a significant occupational health and safety for workers in petrochemical industries. Heat stress is a combination of heat load individual and environmental factors impose on workers’ bodies, which in turn, have impacts on workers’ performance, safety, and health. The present paper is carried out to determine the heat stress levels in workplace and to compare it with allowed Wet Bulb Globe Temperature (WBGT) according to ISO 7243 standard. the present study was carried out in three consecutive weeks in Mehr Petrochemical Complex in South Pars Special Economic Zone in Assaluyeh, 270Km southeast of Bushehr in spring of 2011. The study was carried out on workers in different parts including workers in packaging, mechanics, welding, and store keeping sections. Environmental parameters of dry temperature, natural wet temperature, glowing temperature, and relative humidity were measured to calculate an index for Wet Bulb Globe Temperature according to ISO7243 standard, and metabolism rate was estimated according to ISO 8996 standard. Metabolism level for workers in two groups of mechanics and welding sections according to ISO 8996 standard was 95W/m 2 , and for workers of packaging and store keeping sections calculated as 75W/m 2 . Based on ISO 8996, work load for all four sections was light. The means of weather parameters such as dry temperature, natural wet temperature, glowing temperature, and relative humidity were statistically significant for all four sections. It was also indicated that the highest level of WBGT were obtained for workers in mechanics (33.26±0.21), packaging (32.02±0.2), welding (31.37±0.2), and the lowest level was estimated for store keeping workers (27.4±0.22), with changes being statistically significant. DISCUSSION AND CONCLUSION: findings of the present study indicated significant changes between different groups in measured parameters and calculated indices, which confirm results of previous body of research. Workers in three groups of mechanics, packaging, and welding are exposed to heat stress, and among these three, mechanics workers’ exposure to heat stress is higher, but WBGT index in store keeping work place is lower than allowed level. Thus, they have been experiencing favourable work atmosphere.

Predicting the Three Dimensional Distribution of Gas Pollutants for Industrial-type Geometries in the South Pars Gas Complex Using Computational Fluid Dynamics

Dispersion of air pollutants emitted from an elevated point in industrial environments is a crucial problem. In the current study, the dispersion of gaseous pollutants from stacks and flares of gas refineries (phases 1–5) in the South Pars Gas Complex, located in Iran, is investigated both experimentally and numerically. A computational fluid dynamics (CFD) model is used to determine the dispersion patterns of gaseous pollutants, including CO, SO2, and NO2 in the ambient air. The commercial CFD code, FLUENT, is applied to solve the governing equations by means of the finite volume method. The predicted concentrations of the pollutants in the ambient air are compared with the measured values in specific meteorological conditions. The obtained results indicate an acceptable agreement between the model and the experimental data. Moreover, the results are compatible with the standard k–e turbulence model for simulating the effect of turbulence on the dispersion of pollutants in the petroleum industry.

Improving performance of a neural network model by artificial ant colony optimization for predicting permeability of petroleum reservoir rocks

Over recent years, oil and gas exploration has been beloved due to extended needs for petroleum and energy sources. In this way, the capabilities of intelligent techniques are studied by researchers in different fields of petroleum industry and geosciences, whereas it seems that these techniques can improve the prediction accuracy of exploration and production of the hydrocarbon reservoir. The performance indices of the artificial models have proven to be better than the conventional linear and non-linear statistical models. Artificial intelligence models are extremely useful for reservoir characterization, which requires a high-accuracy prediction for a good exploitation of the oil and gas resources. The present paper introduces an optimized neural network (NN) for predicting permeability based on a relatively new swarm intelligent approach, named ant colony optimization. Ant colony optimization (ACO) is a relatively new computational intelligent approach, which was initially inspired by the observation of ants. The number of neurons in hidden layer, weights and bias are optimized in the proposed NN using the ACO. The data of a gas reservoir in the South Pars Gas Field of Iran was used for analyzing the accuracy of optimized NN in a real case study. Finally, to clarify the advantages of the optimized NN, its outcomes were compared with the results of a simple NN model, in which the aforementioned parameters were determined through a try-and-error process. The MSEs of the optimized and simple NN were equal to 7.95 md and 12.84 md, respectively, which correspond to the correlation coefficient (R) of 0.94 and 0.866, respectively.

Depositional facies and geochemistry of the Kangan formation in the South Pars Field, Persian Gulf (Iran)

The Kangan Formation is one of the largest carbonate reservoirs located in the South Pars Field, which is one of the major gas fields in the central basin of the Persian Gulf. Facies analyses indicate that the Kangan carbonates are formed in four microfacies belts: tidal flat, lagoon, shoal, and shallow open marine, in a platform ramp environment. The predominance of tidal flat sediments along with the oolitic shoal facies and lack of a large shoal reef indicate a homoclinal-ramp system. Major and minor elements and carbon and oxygen isotope values were used to determine the original carbonate mineralogy of the Kangan Formation. The data indicate aragonite carbonate mineralogy in a closed diagenetic system. The Kangan Formation displays a gradual upward increase in δ13C values and variation in δ18O with changing lithologies. Palaeotemperature calculation, based on the heaviest δ18O values in limestone micrites and dolomicrites, range from 36 to 44 °C, respectively. The isotopic compositions of the Kangan carbonates indicate that they were deposited in shallow tropical waters. Stratigraphic analysis indicates four major transgressive and regressive events of nearly two million years’ average duration, which controlled the development of two depositional sequences and their systems tracts.

The origin of oil in the Cretaceous succession from the South Pars Oil Layer of the Persian Gulf

The origin of the oil in Barremian–Hauterivian and Albian age source rock samples from two oil wells (SPO-2 and SPO-3) in the South Pars oil field has been investigated by analyzing the quantity of total organic carbon (TOC) and thermal maturity of organic matter (OM). The source rocks were found in the interval 1,000–1,044 m for the Kazhdumi Formation (Albian) and 1,157–1,230 m for the Gadvan Formation (Barremian–Hauterivian). Elemental analysis was carried out on 36 samples from the source rock candidates (Gadvan and Kazhdumi formations) of the Cretaceous succession of the South Pars Oil Layer (SPOL). This analysis indicated that the OM of the Barremian–Hauterivian and Albian samples in the SPOL was composed of kerogen Types II and II–III, respectively. The average TOC of analyzed samples is less than 1 wt%, suggesting that the Cretaceous source rocks are poor hydrocarbon (HC) producers. Thermal maturity and Ro values revealed that more than 90 % of oil samples are immature. The source of the analyzed samples taken from Gadvan and Kazhdumi formations most likely contained a content high in mixed plant and marine algal OM deposited under oxic to suboxic bottom water conditions. The Pristane/nC17 versus Phytane/nC18 diagram showed Type II–III kerogen of mixture environments for source rock samples from the SPOL. Burial history modeling indicates that at the end of the Cretaceous time, pre-Permian sediments remained immature in the Qatar Arch. Therefore, lateral migration of HC from the nearby Cretaceous source rock kitchens toward the north and south of the Qatar Arch is the most probable origin for the significant oils in the SPOL.