Africa (Sub-Sahara) Oranto Petroleum has signed two production-sharing agreements (PSAs) with Uganda for oil and gas exploration around Lake Albert, the Nigerian company said. The deal covers the Ngassa Shallow and Ngassa Deep plays in blocks near the southern part of Lake Albert, according to the Uganda Ministry of Energy and Mineral Development. The pacts closely followed the signing of a PSA by Australia's Armour Energy that covers the Kanywataba block, a 133-square-mile area that was relinquished by three international companies in 2012 after failed exploration attempts. The agreements with Oranto and Armour involve acreage that was offered in Uganda's first competitive exploration licensing round last year. Uganda discovered oil in 2006 in the Albertine rift basin along the Democratic Republic of Congo border.
Investigation of turbulence dynamics is very important for the understanding of dispersion and transport of pollutants in the marine environment. Specifically, at the surface boundary layer, dispersion phenomena are governed by the interaction of different forces (i.e., currents, waves, and winds) and are characterized by a wide range of temporal and spatial scales (Gallerano et al., 2016). Estimates of turbulence parameters able to describe the interaction of these different forces are required for an accurate prediction of pollutant pathways and concentrations. At present, turbulent dispersion simulations are mainly carried out by using Lagrangian particle models, alternatively based on a Wiener process or a Langevin scheme, which require as input data such turbulence parameters as diffusivity, velocity variance, and Lagrangian time scale (Monti and Leuzzi, 2010; De Dominicis et al., 2012). Besides, a new efficient approach is represented by kinematic chaotic models (Lacorata et al., 2014; Lacorata and Vulpiani, 2017).
Asphaltene deposition is one of the key technical problems in the safe production and transportation of deepwater asphalt base crude oil. This paper analyzes the asphaltene deposition condition and its existence in deepwater crude oil pipeline system by theoretical and experimental study. According to the thermodynamic behavior of crude oil system, the prediction model of its asphaltene deposition conditions is established, and combined with the pressure and temperature drop analysis of deepwater crude oil pipeline system, the prediction method of asphaltene deposition amount and location in deepwater pipelines is preliminarily formed. This study lays a foundation for further study on the flow assurance of deepwater asphalt base crude oil transportation system.
Asphaltene deposition in deepwater pipeline is an important technical problem in the present petroleum industry. Due to the challenging deepwater environments, especially low temperature, adhesion of asphalt base crude oil is strong and liquidity is poor (Sara and Abbas, 2013). Once solid blockage appears in deepwater pipeline, it is very difficult to resume production and remediation cost is extremely high, which presents a high risk to oil production.
According to the special environment of deepwater oil pipeline, the asphaltene deposition condition and its existence in the deepwater oil pipeline system are analyzed based on the changes of pressure and composition of crude oil system. Taking K96 crude oil, KD32 emulsified oil and dewatered oil as the research objects, the rheological properties and corresponding microscopic shapes of the oil samples before and after adding n-heptane are tested and analyzed by using rheology and image analysis technology. Meanwhile, the mathematical model of asphaltene deposition in deepwater crude oil pipeline is established to predict the asphaltene deposition condition, and the prediction method of the asphaltene deposition amount and location in deepwater oil pipeline is initially formed. This is not only necessary but also very challenging to the flow assurance of deepwater asphalt base crude oil transportation system.
AbstractWhen during primary oil production the thermodynamic conditions within the well tubing lie inside the asphaltene deposition envelope (ADE) of the produced fluid, the flocculated asphaltene particles could start depositing on the tubing wall at a certain rate. The above causes a restriction in the tubing ID which results in loss of production. Higher choke settings are required to maintain the same production level until the choke is fully open and the production losses cannot be compensated by opening the choke further. Eventually, the well may ″bridge″ and stop flowing completely or continue flowing at an extremely small flow rate in a rather ″burping″ way where the flow starts and stops at different time intervals on its own volition. Understanding when and how to intervene not only diminishes the risk of unsuccessful or, even worst, detrimental operations but also may increase the well’s productivity throughout its life.This paper presents a methodology of first determining the ADE in the lab, along with the asphaltene particle size distribution as a function of pressure and temperature. Moreover, asphaltene deposition rates for the tubing conditions can be measured using high pressure and temperature coaxial cylinder technology. Utilizing this technique allows to quantify the amount of flocculated asphaltenes that will deposit under the expected conditions. From that data, it is illustrated how a well-equipped simulator can be, initially, tuned to predict the phase behavior measured in the lab along with the deposition rates. Finally, the simulator can then run the production scenarios available into the future, predicting the impact of asphaltene deposition in the tubing and the resulting loss of production and quantify the asphaltene deposit. It is apparent that this information can prove invaluable in the design of the well completion and flowline along with the facilities and help further refine the understanding of the expected production problems. This methodology is especially important in offshore satellite tieback wells expected to undergo asphaltene deposition.
Adel, N. Abu (Australian College of Kuwait) | Abdullah, F. (Australian College of Kuwait) | Al-Kanderi, H. (Australian College of Kuwait) | Tesiari, E. (Australian College of Kuwait) | Ghafoori, S. (Australian College of Kuwait) | Alkazimi, M. A. (Kuwait Oil Company) | Al-Bazzaz, W. H. (Kuwait Institute For Scientific Research)
Extreme heavy oil <5 °API is considered a type of unconventional tight oil, which will require a challenging petroleum production system for future new-generation extreme heavy oil or bitumen carbonate reserves. This oil is abundant in great amounts around the globe, yet is extremely difficult to produce due to its solid-like physical state locked deep underground. The world strategy eventually will shift focus to this type of oil since conventional and other less-quantitative-difficult reservoirs are continuously depleting. The interest of this study is directed towards a specific type of unconventional oil, which is available in tight carbonate reservoirs. Extreme heavy oil <5 °API exists in large quantities in Kuwaiti fields. This study presents a novel heavy oil classification especially for <5 °API crude oil types as well as their potential recoveries. All recoveries considered for this study are bench-scale laboratory physical experiments with toluene, de-ionized water and water-aided surfactants augmented with applied field thermal 25 °C, 135 °C, 225 °C and 315 °C heat treatments.
The main objective for this research is to model five signature atoms available in almost all heavy crude oils: carbon, hydrogen, nitrogen, sulfur, and oxygen (CHNSO). These CHNSO fingerprints determine qualitatively and quantitatively the potential amount and quality of future extreme heavy crude oil recovery. An Artificial Intelligence (A.I.) neural network algorithm is developed for all possible conjecture atoms. A Multiple Layer Forward Feed (MLFF) learning system is designed, trained and applied for developing the A.I. neural network. Forty-one recovery models are manifested in this study, clustered in possible atom conjecture operational base-function domains, which are unary (one atom), binary (two atom), ternary (three atom), quaternary (four atom) and quinary (five atom) approach models.
The main technological motivation for CHNSO research is finding the optimized conventional EOR recovery efficiency factor that will extract <5 °API oil. The model predicts the recovery potential factor in a classic, optimum and conventional economic scenario, considering the unconventional environmental impact, crude oil subsurface-mobility issues and technology limitations used as current economic challenges.
The general summary of results suggest that CHNSO models are useful in better understanding and better predicting <5 °API oil recoveries. The three-atom nitrogen-sulfur-oxygen (NSO) ternary conjecture model has a significant impact regarding heavy crude oils, maximizing recovery in general, and extreme heavy oil potential recovery in particular, in regards to the difficult mobility of this type of crude oil.
Last year, 244 million tonnes per annum (MTPA) of liquefied natural gas (LNG) was transported around the globe. The recent shale gas revolution, coupled with low domestic natural gas prices, has led many operators in the US to consider export of their gas to more lucrative markets in Asia and Europe. More than 25 LNG projects have been proposed in the US, totaling a capacity of more than 200 MTPA. The Federal Energy Regulatory Commission (FERC) has approved five LNG terminals in the US. Most experts believe US LNG export capabilities will be about 10% of domestic production in the coming years, which puts LNG export estimates between 6 and 8 Bscf/D. The question remains, where will all of this gas come from?
The vast amount of increased gas production in the onshore US will come from growth in the shale gas plays. These plays, including the Barnett, Fayetteville, Woodford, Marcellus, Haynesville, Eagle Ford, and others, will be further exploited to supply domestic needs and the new LNG export demand. A typical proposed US LNG train is estimated to output 4.5 MTPA, which requires an input of around 636 MMscf/D. It will take a significant quantity of shale gas wells to deliver enough gas to keep a train at full capacity. This paper addresses the impact that LNG- driven natural gas demand will have on the future development of shale gas plays in the US.
Increased demand on domestic US natural gas supplies will be met with increased development drilling. In order to quantify the impact of LNG exports on the market, this paper considers the number of horizontal shale gas wells needed to supply one LNG train continuously. Shale gas basins around the US were studied to estimate both the number of wells needed to supply a train initially and the number and frequency of future wells that will need to be drilled to maintain the train at full capacity. Current activities, including infrastructure and rig counts, decline trends, economics, and drilling times are included in the analysis.
This paper discusses the impact future increased LNG gas demand will have on the field development plans of shale gas plays and identifies probable future activity levels in shale gas basins due to exploitation activity focused on LNG supply. The feasibility of LNG export from the US is a topic of debate, and this paper will provide context and rationale for the discussions.
The identification of dominant failure modes of large structures is a subject of great importance in modern engineering, because it offers the opportunity to monitor the evolution of failure mechanisms in time and space, thus allowing the designer to interfere with system reliability by reinforcing or altering the structural system, either during the design or the operational phase. The purpose of this investigation is to identify the dominant failure modes of an existing offshore platform of jacket type under dynamic loading. For the stochastic analysis describing the above mentioned system, the random variables being selected are the yield stresses of the n elements of the structure. A genetic algorithm is implemented for the selective searching of n-dimensional space of random variables in order to obtain dominant failure modes in decreasing order of their probability of occurrence. Then, the importance of a failure mode is approximated by matching each failure mode to the respective safety index,.
Tsiambaos, G. (National Technical University of Athens) | Sabatakakis, N. (University of Patras) | Rondoyanni, Th. (National Technical University of Athens) | Depountis, N. (University of Patras) | Kavoura, K. (University of Patras)
Some typical landslide phenomena in Western Greece, in terms of the geological composition and structure of the affected materials, induced by heavy rainfalls are thoroughly studied and analyzed. The studied cases involved composite landslides on Flysch and Neogene weak rock materials that constitute the most critical landslide prone geological formations in Greece. The studied cases named Platanos, Platanitis and Karya include representative landslide sites as regards to the geological composition and structure of the displaced formations. Thus: (a) flysch formation includes different lithological units as shales, marls, siltstones, sandstones and conglomerates and is closely related to the Alpine orogenesis, suffering intense past tectonic movements and (b) the Plio-Pleistocene sediments include clayey marls, marlstones and siltstones. The investigated landslides , affecting mainly transportation routes, are closely related to heavy rainfalls induced by extreme meteorological events and are controlled by active fault tectonics. Long term movement monitoring using borehole inclinometers and surface benchmarks showed that landslides control was effective only when the proper stabilization measures were taken.
Landslides represent a major threat to human life, property, infrastructure and natural environment in most regions of the world. They are recognized by the scientific and politic authorities as having a major socio-economic impact and they represent a significant hazard for the population and the properties in particular locations. Landslide hazard expressed as the probability of occurrence within a reference time period and is a function of the spatial and temporal probability (Varnes, 1984; Guzzetti et al. 1999; Lee and Jones, 2004). The spatial probability of landslide initiation (susceptibility) is mainly related to static causal factors (slope inclination, material properties, etc.), while temporal probability is mainly related to dynamic causal factors such as rain input, increased groundwater levels and drainage, earthquakes, etc. (Van Westen et al. 2005).
One of the most frequent causes of landslides in the Western part of Greece is a change in groundwater levels, either by natural drainage conditions or by an increase in groundwater due to periods of excessive rainfall. The presence of groundwater affect slope stability by increasing the effective weight of the saturated materials, creating appreciable pore pressure and tending to weaken soft rocks and unconsolidated materials. Other factors such as: variant lithological composition, intense folding and jointing as well as high relief energy favor the manifestation of such phenomena. However, the predominant factors relative to the triggering effects are mainly heavy rainfalls and active fault tectonics. The interrelation between landslide events and precipitation for Western Greece was initially established by Koukis et al. (1996).
The oil and gas sector is a topic of the utmost importance nowadays, as its business turnover moves several billion euro every year. Moreover this sector is strategic both globally and nationally. This study is realized by “Bicocca” University of Milan supporting the Directorate General for Mineral and Energy Resources of the Italian Ministry of Economic Development in application of the Legislative Decree April 3rd, 2006 n0152 as modified by the art. 35 of the Legislative Decree June 22nd, 2012 n0.83 about the offshore safety in accordance to the objective of improvement knowledge about the geology of offshore area. Within this aim this paper shows the new offshore exploration and production (E&P) perspectives for what is concerning Italian continental shelf (as defined by the UNCLOS,1982 ), based on the examination of national data.
With the Ministerial Decree of August 19th 2013, all areas open to hydrocarbon E&P activities were rescheduled and a new area called “Zone E” was opened in the west side of the Sardinian offshore. With the new interest for the deep offshore and for reservoirs with complex geology there is need for the improvement in knowledge about the geological and tectono-stratigraphic settings as well as in definition of the potentiality of the area, through the assessment of the presence of petroleum system’s characteristic elements. The goal of this study is to review existing literature, collect and preliminary process data about the area and give an overview of the potential presence of "undiscovered” resources of hydrocarbon in the west Sardinian offshore.
This study models recovery of deep Tar-Mat available in substantial amounts in the Middle Eastern general and in Kuwait in particular as next generation and strategic reserves for extreme viscous and immobile solid-like unconventional oil. The study considers three unconventional different physical models. These physical models’ fundamentals are generated, validated and predicted hence formulated using conventional extraction and unconventional geochemistry technologies. The first conventional recovery physical model is the liquid extracts of Saturates, Aromatics, Resin, Resin-to-Asphaltene (RAS) and Asphaltenes yielding unconventional model (RAS Model). The second unconventional recovery physical model is the elemental fingerprinting of carbon, hydrogen, nitrogen, sulfur and oxygen (H/C Aspect-Ratio Model). The third unconventional recovery physical model is the rock evaluation pyrolysis.
In this study, sixty experimental lab data are performed on five fresh tar mat samples. Also three EOR agents are proposed for recovery techniques, toluene solvent, de-ionized water and surfactant-aided de-ionized water. Since four proposed thermal EOR techniques have been used 25°C, 135°C, 225°C and 315°C temperatures for the recovery, all recovery models honor systematic temperature variation for the recovery.
All three unconventional models are laboratory data-driven models, which will attempt to define recovery patterns, quantify novel phenomenon, and develop new relationships. Each physical Model will have the ability to assess the recovery application for this unconventional reservoir. Assessing the recovery starts with unconventional measuring the API density that is less than 5 °API henceforth the viscosity and the mobility of Tar-Mat-solid-like oil. Then monitor the recovery as the type of EOR agent and temperature conditions are elevated during the recovery process. On the basis of recovery findings unconventional models, new tools will be developed for engineers, geologists and oil companies to prospect this strategic reservoir.