Gas Recovery Rate Research Articles

Experimental study on the hydrate dissociation in porous media by five-spot thermal huff and puff method

A novel method for hydrate production named “Five-spot thermal huff and puff (HP-5S)” is designed and employed to investigate the behaviors of hydrate dissociation in the Cubic Hydrate Simulator (CHS). This method uses the thermal huff and puff method in a five-spot well system. In addition, the experiments with the methods of the five-spot thermal huff and puff in conjunction with depressurization (HP-5S-D), the heat stimulation with a five-spot well (HS-5S), the heat stimulation in conjunction with depressurization with a five-spot well (HS-5S-D), the thermal huff and puff (HP), and the huff and puff in conjunction with depressurization (HP-D), are also carried out in this work. The energy efficiencies, thermal efficiencies, gas recoveries, and average gas production rates are used to evaluate these production methods. The analysis of hydrate decomposition shows that the thermal huff and puff method in a five-spot well system is superior to that in a single vertical well on the aspects of the energy efficiency, thermal efficiency, gas recovery, and average gas production rate. The HP-5S-D method, which can obtain the highest gas recovery, thermal efficiency, and energy efficiency, is the optimal method for hydrate production in this work.

Carbon Dioxide Separation Technology from Biogas by “Membrane/Absorption Hybrid Method”

“Membrane/absorption hybrid method” is a technology developed by Research Institute of Innovative Technology for the Earth (RITE) aiming to separate I collect carbon dioxide in exhaust combustion gas at low cost and in high purity. RITE and Taiyo Nippon Sanso Corporation (TNSC) had developed a biogas concentration unit that utilizes “membrane / absorption hybrid method” jointly. We had succeeded to improve the regeneration efficiency of carbon dioxide absorption solution for circulated use while maintaining high methane gas recovery rate, and improved the recovery rate of carbon dioxide.Moreover, it turned out that separation cost can be reduced by using the separation process using the source of surplus waste heat at a biogas generation site.

Thermo-hydro-mechanical modeling of carbon dioxide injection for enhanced gas-recovery (CO2-EGR): a benchmarking study for code comparison

The objective of this paper was to investigate the THM-coupled responses of the storage formation and caprock, induced by gas production, CO2-EGR (enhanced gas recovery), and CO2-storage. A generic 3D planer model (20,000 × 3,000 × 100 m, consisting of 1,200 m overburden, 100 m caprock, 200 m gas reservoir, and 1,500 m base rock) is adopted for the simulation process using the integrated code TOUGH2/EOS7C-FLAC3D and the multi-purpose simulator OpenGeoSys. Both simulators agree that the CO2-EGR phase under a balanced injection rate (31,500 tons/year) will cause almost no change in the reservoir pressure. The gas recovery rate increases 1.4 % in the 5-year CO2-EGR phase, and a better EGR effect could be achieved by increasing the distance between injection and production wells (e.g., 5.83 % for 5 km distance, instead of 1.2 km in this study). Under the considered conditions there is no evidence of plastic deformation and both reservoir and caprock behave elastically at all operation stages. The stress path could be predicted analytically and the results show that the isotropic and extensional stress regime will switch to the compressional stress regime, when the pore pressure rises to a specific level. Both simulators agree regarding modification of the reservoir stress state. With further CO2-injection tension failure in reservoir could occur, but shear failure will never happen under these conditions. Using TOUGH-FLAC, a scenario case is also analyzed with the assumption that the reservoir is naturally fractured. The specific analysis shows that the maximal storage pressure is 13.6 MPa which is determined by the penetration criterion of the caprock.

Flue-Gas Carbon Capture on Carbonaceous Sorbents: Toward a Low-Cost Multifunctional Carbon Filter for “Green” Energy Producers

A low-pressure Carbon Filter Process (patent pending) is proposed to capture carbon dioxide (CO2) from flue gas. This filter is filled with a low-cost carbonaceous sorbent, such as activated carbon or charcoal, which has a high affinity (and, hence, high capacity) to CO2 but not to nitrogen (N2). This, in turn, leads to a high CO2/N2 selectivity, especially at low pressures. The Carbon Filter Process proposed in this work can recover at least 90% of flue-gas CO2 of 90%+ purity at a fraction of the cost normally associated with the conventional amine absorption process. The Carbon Filter Process requires neither expensive materials nor flue-gas compression or refrigeration, and it is easy to heat integrate with an existing or grassroots power plant without affecting the cost of the produced electricity too much. An abundant supply of low-cost CO2 from electricity producers is good news for enhanced oil recovery (EOR) and enhanced coal-bed methane recovery (ECBMR) operators, because it will lead to higher oil and gas recovery rates in an environmentally sensitive manner. A CO2-rich mixture that contains some nitrogen is much less expensive to separate from flue-gas than pure CO2; therefore, mixed CO2/N2-EOR and CO2/N2-ECBMR methods are proposed to maximize the overall carbon capture and utilization efficiency.

How sorption-induced matrix deformation affects gas flow in coal seams: A new FE model

The influence of sorption-induced coal matrix deformation on the evolution of porosity and permeability of fractured coal seams is evaluated, together with its influence on gas recovery rates. The porosity-based model considers factors such as the volume occupied by the free-phase gas, the volume occupied by the adsorbed phase gas, the deformation-induced pore volume change, and the sorption-induced coal pore volume change. More importantly, these factors are quantified under in situ stress conditions. A cubic relation between coal porosity and permeability is introduced to relate the coal storage capability (changing porosity) to the coal transport property (changing permeability). A general porosity and permeability model is then implemented into a coupled gas flow and coal deformation finite element model. The new FE model was used to compare the performance of the new model with that of the Palmer–Mansoori model. It is found that the Palmer–Mansoori model may produce significant errors if loading conditions deviate from the assumptions of the uniaxial strain condition and infinite bulk modulus of the grains. The FE model was also applied to quantify the net change in permeability, the gas flow, and the resultant deformation in a coal seam. Model results demonstrate that the evolution of porosity and of permeability is controlled by the competing influences of effective stresses and sorption-based volume changes. The resulting sense of permeability change is controlled by the dominant mechanism.

Affecting Factors and Improving Measures for Converter Gas Recovery

Abstract To change the undesirable present situation of recovering and using converter gas in steel plants in China, the basic approaches to improving the converter gas recovery rate were analyzed theoretically along with the change curves of the converter gas component content, based on the converter gas recovery system of Baosteel No. 2 steel-making plant. The effects of converter device, raw material, air imbibed quantity, recovery restricted condition, and intensity of oxygen blowing on the converter gas recovery rate were studied. Among these, the effects of the air imbibed quantity, recovery restricted condition, and intensity of oxygen blowing are remarkable. Comprehensive measures were put forward for improving the converter gas recovery from the point of devices, etc., and good results were achieved.

Influence of Initial Water Saturation on Recovery by Spontaneous Imbibition in Gas/Water/Rock Systems and the Calculation of Relative Permeability

Summary It has been a challenge to understand why recovery by spontaneous imbibition could both increase and decrease with initial water saturation. To this end, mathematical models were developed with porosity, permeability, viscosity, relative permeability, capillary pressure, and initial water saturation included. These equations foresee that recovery and imbibition rate can increase, remain unchanged, or decrease with an increase in initial water saturation, depending on rock properties, the quantity of residual gas saturation, the range of initial water saturation, and the units used in the definitions of gas recovery and imbibition rate. The theoretical predictions were verified experimentally by conducting spontaneous water imbibition at five different initial water saturations, ranging from 0 to approximately 50%. The effects of initial water saturation on residual saturation, relative permeability, capillary pressure, imbibition rate, and recovery in gas/water/rock systems by cocurrent spontaneous imbibition were investigated both theoretically and experimentally. Water-phase relative permeabilities and capillary pressures were calculated with the experimental data of spontaneous imbibition. Experimental results in different rocks were compared.

Effects of Processing on Electric Response of Carbon Black Filled Poly(methyl methacrylate) Composites against Organic Solvent Vapors

Carbon black filled poly(methyl methacrylate) (CB/PMMA) composites were fabricated by solution mixing and polymerization filling, respectively. The effects of processing conditions on electrical conductivity of the composites and their electric responsivity against organic solvent vapors were investigated. The experimental results showed that molecular weight of the polymer matrix, carbon black content, and the composite film thickness greatly influence the response behaviors of the composites in solvent vapors. Furthermore, the composites prepared by polymerization filling have higher gas sensitivity, response rate, recovery rate, and reproducibility as compared to the composites by solution mixing. The sensing performance of the composites is found to be closely related to the microstructure of the materials, which provides possibilities for further improve the overall properties of the composites by altering the processing parameters.

Characteristics of the C Shale and D Shale Reservoirs, Monterey Formation, Elk Hills Field, Kern County, California: ABSTRACT

The upper Miocene C Shale and D Shale reservoirs of the Elk Hills Shale Member of the Monterey Formation have cumulative oil and gas production much higher than the originally estimated recovery. These San Joaquin basin reservoirs are the lowest of the Stevens producing zones at Elk Hills and currently produce from a 2800-acre area on the 31 S anticline. The C Shale contains lower slope and basin plain deposits of very fine grained, thinly bedded, graded turbidites, pelagic and hemipelagic claystone, and slump deposits. Although all units are oil-bearing, only the lower parts of the graded turbidity intervals have sufficient horizontal permeability to produce oil. The D Shale consists of chart, claystone, carbonates and slump deposits, also originating in a lower slope to basin plain setting. All D Shale rock types contain oil, but the upper chart interval is the most productive. The chart has high matrix porosity, and due to a complex horizontal and vertical microfracture system, produces at a highly effective rate. Core samples indicate more oil-in-place is present in the thin, graded C Shale beds and in the porous D Shale chart than is identifiable from conventional electric logs. High gas recovery rates are attributed mostlymore » to this larger volume of associated oil. Gas also enters the reservoirs from the adjacent 26R reservoir through a leaky normal fault. Significant gas volumes also may desorb from immature organic material common in the rock matrix.« less

Geochemical Effects of Cap-Rock Leakage Above Gas Reservoirs: Distribution of Light Hydrocarbons to Monitor Diffusive Losses: ABSTRACT

An aspect of greater interest to hydrocarbon exploration in certain areas concerns the sealing efficiency of cap-rocks above gas reservoirs. In order to search for evidence of diffusive gas losses through cap-rocks, the distribution of light hydrocarbon (C1-C6) was studied in a gas-bearing sequence of NW-Germany. From an exploration well in Northwest-Germany 340 fresh cutting samples covering a depth range from 2750m down to 3986m were sealed in metal cans and immediately analyzed by Headspace-Gas-Chromatography (HS-GC). Some method development had to be carried out to ensure satisfying gas recovery rates from cutting samples and reproducible compound separation and identification. Two main intervals have been studied by closely spaced samples within the Permian Zechstein and the Triassic Bunter. The Zechstein sequence included the carbonate gas reservoir horizon (Ca2) and cap rock lithologies of anhydrites and halite of 300 m thickness. The Bunter interval mainly consisted of gas-bearing sandstones overlayed by thick homogeneous claystones of several meters thickness that could be examined for evidence of diffusive gas losses. The analytical requirement was to fully separate the LHC from C1 to C6 in order to allow calculation of selected compound ratios which are likely to indicate redistribution of light hydrocarbon by diffusion, e.g.more » compound of high diffusivity in relation to compounds of low diffusivity. This approach does not require the determination of absolute amounts of gaseous hydrocarbons which causes problems with respect to accuracy and reproducibility. Furthermore, TC-, TOC-, TIC- and sulfur-contents were measured to verify whether indigenous organic matter contents lead to in situ generation of gaseous hydrocarbons in those cap-rock sequences.« less

Total Automatic Control of BOF on a Modern Control Theory

A dynamic model using state-space method was developed and commercialized for the control of the molten steel composition and temperature in the steel-making process, and the prediction of the exhaust gas in OG process. This model estimates state variables representing the steel-making process using Kalman Filter, and controls them continuously during blowing. As a result, the hitting rate for the end point composition and temperature of molten steel has reached over 95% showing a great improvement over the past results, and the gas recovery rate to theoretical one has greatly increased to 85% from conventional 70%. The full automatic operation of BOF and OG process has been realized.