Associated Gas Utilization Using Gas Turbine Engine, Performance Implication—Nigerian Case Study

Typically, crude oil production in Nigeria always accompanied by surface production of associated gas. With little associated gas recovery facilities in place, majority of associated gas is continuously flared with few portions re-injected into the reservoir for enhance oil recovery (EOR). In addition to environmental hazards, wasting substantial amount of produced associated gas is deemed detrimental to a country currently generating less than 54% of its electric power requirement. Onsite power generation as one of the many means of utilization of associated gas has been conceived. Conversely, the availability and performance of the gas turbine engine for onsite associated gas utilization requires evaluation owing to variations in associated natural gas composition globally and the dependency of associated gas production on reservoirs and oil production activities. This paper presents an analytical investigation of gas turbine engine inspired by GE LMS100 frame engine for onsite utilization of associated gas in Nigeria. Gas turbine performance results are presented and performance parameters are compared against typical commercial natural gas grade.

Effects of Stylosanthes scabra Forage Supplementation on in Vitro Gas Production and Fiber Degradation of Eragrostis Grass Hay

Natural pastures constitute a major component of ruminant livestock feed, and are the most cost-effective feed resource available for smallholder subsistence farmers. However, this feed resource does not meet animal nutritional requirement due to deficiency in nitrogen, energy and minerals. In addition, at maturity lignification is the major concern since it reduces digestibility and contributes to methane emission. Thus, the objective of this study was to evaluate the effect of supplementing low-quality Eragrostis grass hay with five (9281, 11,252, 11,255, 11,595 and 11,604) selected Stylosanthes scabra accessions on in vitro ruminal fermentation and neutral detergent fiber degradation. Therefore, in vitro study was conducted on grass hay, accessions and the mixture of grass hay with each accession included at two (15%, 30%) levels. The substrates (grass hay, accessions and the mixtures) were incubated in separate serum bottles for 72 h. Neutral detergent fiber (NDF) of the accessions ranged from 300 to 350 g/kg DM with crude protein (CP) value ranging from 177.5 to 184.1 g/kg DM. Eragrostis grass hay had NDF value of 813 g/kg DM, with CP value of 34.3 g/kg DM. Grass hay fermented slowly, it took 30 h for grass hay to produce gas volume above 50 mL, while Stylosanthes scabra accessions took 12 h. Supplementing grass hay with accessions significantly improved fermentation. However, it was observed that 15% inclusion took 30 h to produce gas volume above 50 mL, whereas at 30% inclusions it took 24 h for accession 9281, 11,595 and 11,604. Accession 11,604 improve grass fermentation by almost three times the value of grass hay in 2 h. Grass hay supplemented with accession 11,604 at 30% had a positive associative effect and significantly improved NDF degradability. In conclusion, accession 11,604 may be fed strategically as forage supplement to low-quality forage for ruminants.

Occurrence and influence of residual gas released by crush methods on pore structure in Longmaxi shale in Yangtze Plate, Southern China

The composition of gas released under vacuum by crushing from the gas shale of Longmaxi Formation in Upper Yangtze Plate,Southern China was systematically investigated in this study.The effect of residual gas release on pore structures was checked using low-pressure nitrogen adsorption techniques.The influence of particle size on the determination of pore structure characteristics was considered.Using the Frenkel-Halsey-Hill method from low-pressure nitrogen adsorption data,the fractal dimensions were identified at relative pressures of 0‒0.5 and 0.5‒1 as D1 and D2,respectively,and the evolution of fractal features related to gas release was also discussed.The results showed that a variety component of residual gas was released from all shale samples,containing hydrocarbon gas of CH4(29.58%‒92.53%),C2H6(0.97%‒2.89%),C3H8(0.01%‒0.65%),and also some non-hydrocarbon gas such as CO2(3.54%‒67.09%)and N2(1.88%‒8.07%).The total yield of residual gas was in a range from 6.1μL/g to 17.0μL/g related to rock weight.The geochemical and mineralogical analysis suggested that the residual gas yield was positively correlated with quartz(R^2=0.5480)content.The residual gas released shale sample has a higher surface area of 17.20‒25.03 m^2/g and the nitrogen adsorption capacity in a range of 27.32‒40.86 ml/g that is relatively higher than the original samples(with 9.22‒16.30 m^2/g and 10.84‒17.55 ml/g).Clearer hysteresis loop was observed for the original shale sample in nitrogen adsorption-desorption isotherms than residual gas released sample.Pore structure analysis showed that the proportions of micro-,meso-and macropores were changed as micropores decreased while meso-and macropores increased.The fractal dimensions D1 were in range from 2.5466 to 2.6117 and D2 from 2.6998 to 2.7119 for the residual gas released shale,which is smaller than the original shale.This factor may indicate that the pore in residual gas released shale was more homogeneous than the original shale.The results indicated that both residual gas and their pore space have few contributions to shale gas production and effective reservoir evaluation.The larger fragments samples of granular rather than powdery smaller than 60 mesh fraction of shale seem to be better for performing effective pore structure analysis to the Longmaxi shale.

Covalent Bonds Creation between Gas and Liquid Phase Change: Compatibility with Covalent and Even-Odd Rules Based on a “Specific Periodic Table for Liquids”

A decrease in temperature will eventually turn a gas into liquid and then into a solid. Each of these phase change shows a higher degree in cohesion of molecules. While it is usually admitted that molecules in solids form additional connections, the cohesion of molecules in liquids is usually explained by changes in kinetics of molecules. Given that the density of a solid is nearly the same than that of a liquid, the present paper assumes a different stand and considers that connections between molecules must be similar in liquids and in solids. The difference between gas, in which molecules are entirely loose, and liquid, is therefore the presence of an additional connection between gaseous molecules. This paper describes how and where these connections are built with the help of a few rules and a “specific periodic table for liquids”. The coherence of this approach is reinforced by its capacity to explain phase change of forty well-known molecules containing inorganic and organic elements.

The Effect of Gas Production, Utilization, and Flaring on the Economic Growth of Nigeria

The extent to which a country develops is anchored around its resources;and this is evidenced in how the revenue derived from natural resources (especially the oil and gas industries) has influenced national development strategies. This notwithstanding, the existence of natural resources does not always translate to development, as these often times lead to complacency and mismanagement;Nigeria may have suffered from this. This paper establishes the impact of gas production, utilization, and flaring on the estimated monetary value of the goods and services produced in Nigeria (GDP), using multiple linear regression analysis. The result shows that while gas utilization has a positive impact on the nation’s GDP, gas production and flaring are negatively associated with GDP. The paper concludes that for these to positively stimulate economic growth, there is need to invest more in infrastructure in the industry, and review the regulatory framework guiding operations of the oil and gas industry.

Indicators of δ^(13)C and δ^(18)O of gas hydrate-associated sediments

The analyses of δ13C and δ18O of gas hydrate-associated sediments from two cores on Hydrate Ridge in Cascadia convergent margin offshore Oregon, eastern North Pacific show the values of δ13C from-29.81‰ to -48.28‰(PDB) and δ18O from 2.56‰to 4.28‰ (PDB), which could be plotted into a group called typical carbonate minerals influenced by the methane in cold venting. Moreover, the values of δ13C and δ18O show a consistent trend in both cores from top to bottom with increasing of δ13C and decreasing of δ18O. This trend could be explained as an effect caused by the anaerobic oxidation of methane (AOM) in depth and the oxygen fraction during the formation of gas hydrate in depth together. These characteristics of δ13C and δ18O indicate that the gas hydrate-associated sediments are significantly different from the normal marine carbonates, and they are deeply influenced by the formation and evolution of gas hydrate. So, the distinct characteristics of δ13C and δ18O of gas hydrate-associated

In-depth study on the solubility of elemental sulfur in sour gas mixtures based on the Chrastil's association model

Accurately predicting the solubility of elemental sulfur in sour gas mixtures is a primary task.As a current and widely-used model on the solubility of elemental sulfur in sour gas mixtures,Chrastil's association model has a big error in the process of predicting experimental data based on different fitting methods.This paper combined with experimental data reported by relevant scholars about elemental sulfur solubility in sour gases and selected density,temperature and pressure as three important influential factors.According to different fitting methods,we can calculate the correlation parameters in Chrastil's model.Then different solubility formulas can be used to predict the solubility of elemental sulfur in sour gas mixtures.Through in-depth research and analysis of Chrastil's solubility model from numerical aspects,it's easy to find the irrationality about Chrastil's solubility model and fitting methods.Especially in fitting methods,further improvement of the fitting method is proposed and used to predict the solubility of elemental sulfur in sour gas mixtures.The calculation results show that some improvements of the predicting precision have been achieved by using the improved fitting method in Chrastil's association model.

Characterization of the pore system in an over-mature marine shale reservoir:A case study of a successful shale gas well in Southern Sichuan Basin,China

During the past two years the shale gas exploration in Southern Sichuan basin received some exciting achievements.Data of a new appraisal well showed that the gas producrtions of vertical well and horizontal well are^1.5×104 m3/day/well(with maximum^3.5×104 m3/day/well)and^12.5×104 m3/day/well(with maximum^40×104 m3/day/well),respectively,indicating a good gas potential in this area.Eight core samples from the reservoir were investigated by using a carbon sulfur analyzer,microphotometry,x-ray diffractometry,field-emission scanning electron microscopy(FE-SEM),mercury injection porosimetry(MIP),and low-pressure nitrogen adsorption to obtain a better understanding of the reservoir characteristics of the Upper OrdovicianeLower Silurian organic-rich shale.Results show that the total organic carbon(TOC)content ranges from 0.5%to 5.9%,whereas the equivalent vitrinite reflectance(VRr)is between 2.8%and 3.0%.Pores in the studied samples were observed in three modes of occurrence,namely,interparticle pores,intraparticle pores,and intraparticle organic pores.The total porosity(P)ranges from 1.6%to 5.3%,and MIP data sets suggest that pores with throats larger than 20 nm contribute little to the pore volume.Low-pressure N2 adsorption isotherms indicate that the total specific surface area(SBET)ranges from 9.6 m2/g to 18.9 m2/g,and the pore volume(V)ranges from 0.011 cm3/g to 0.020 cm3/g.The plot of dV/dW versus W shows that the fine mesopores(pore size(BJH)<4 nm)mainly contribute to the pore volume.The P,SBET,and V show a good positive correlation with TOC and a weak positive correlation with the total clay mineral content,thus indicating that the nanopores are mainly generated by the decomposition of organic matter.The reservoir characteristics of the Upper OrdovicianeLower Silurian organic-rich shale are comparable with commercial shale gas plays in North America.The sample gas contents with TOC>2%are more than 3.0 m3/ton.The observation can be a good reference for the future exploration and evaluation of reservoir in this area.

Isotopic composition charac-teristics and identification of immature and low-mature oils

Isotopic composition characteristics and the significance of immature and low-mature oils are first systematically discussed. The carbon isotopes of the whole oil can be divided into two groups, one has δ13C main peak values ranging from -30‰ to -29 and the other from -27‰ to -25‰, they are related to lacustrine and salt-lake facies or swamp facies, respectively. The carbon isotopic fractionation among different group components is relatively small, usually less than 2‰ and the biggest difference in fractionation often occurs between saturated and aromatic fractions. Their δD values vary between -180‰ and -130‰. The main peak of their δD values concentrates between -170‰ and -150‰, suggesting a domination of lacustrine facies. However, the secondary peak ranges from -160‰ to -150‰, showing a frequent salinization of paleo-water bodies. The average δ13C values of the methane vary between -50‰ and -52‰, about 10‰ lighter than those of mature oils. There is a relatively good