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Forecasting deliverability in shale gas reservoirs accurately has received much attention in the industry in recent years. Most wells in shale gas reservoirs are horizontal with multiple fractures, and it has been widely recognized that the dominant early flow regime is usually long-duration transient flow. The most popular method for analyzing linear flow is the plot of rate-normalized pressure versus square root of time, where the pseudo-pressure is employed for gas. However, the pseudo-pressure employed approach is difficult to handle by hand than the pressure employed approach. The purpose of this work is to evaluate the accuracy of pseudo-pressure employed method for analyzing gas rate in shale gas reservoirs, and establish which method is the most simple and accurate for reserve estimation. Based on a number of numerically simulated cases, comparisons between the pseudo-pressure and pressure employed methods for estimating gas rate are made. It is shown that the pressure employed method yields the gas rate that not quite accurately match the simulated values, however, as the same general parameters, the pseudo-pressure employed method really does not improve this inaccuracy. Accordingly, the pressure employed approach is a good and simple method for forecasting gas rate. In addition, depending on the simple hand method, a modification approach is proposed by incorporating constant factors to forecast the gas rate with more confidence. This work will provide an efficient guidance to assist analysts in evaluating hydrocarbon deliverability rapidly and efficiently in shale gas reservoirs. [ABSTRACT FROM AUTHOR]

Physical and numerical simulations of subsurface upgrading by use of solvent deasphalting (SSU-SDA) at laboratory conditions will be presented with a heavy crude oil and propane as a solvent. In this work, 1D propane-flood experiments were performed in a live-crude-oil-saturated (8.8° API) sand at 120°F and 1,000 psi (7.58 MPa). The results showed oil recovery of 85 wt%, with increases of ° API value up to 14° API for the produced crude oil. By use of laboratory-characterization data, a new asphaltene-precipitation model was developed that involves four pseudocomponents (deasphalted oil, heavy fraction, and soluble and solid asphaltenes) and three pseudochemical reactions to numerically simulate the laboratory experiments. [In this text, asphaltenes are the fraction of the crude oil that precipitates in paraffins (propane or heptane) and are soluble in aromatics or chlorine-containing solvents (CH2Cl2)]. History match showed very good agreement between the experimental and calculated oil and gas rates and cumulative oil. Also, reasonably good match between laboratory and theoretical ° API value of the produced oils was found throughout the propane-flood experiments. By use of this model, a field-scale well pair in steam-assisted-gravity-drainage (SAGD) configuration was simulated for steam only and two steam/propane cases [10:1- and 1:1-vol% ratio, as measured by liquid volume of solvent per cold water equivalent (CWE) of steam] in a typical heavy-crude-oil reservoir. Results showed accelerated oil production and higher ° API values of crude in the presence of propane in comparison with the steam-only case. For the 1:1 steam/propane case, the model predicted that the oil quality improved enough to make the oil transportable through a pipeline. This work finds that SSU-SDA continues to show promise as a viable oil-recovery and -upgrading process when the complex downhole physics is modeled. It is predicted that higher propane/steam ratios are needed during SSU-SDA compared with historical solvent-based enhanced-oil-recovery field pilots to capture both the oil-recovery and -upgrading benefits of this process. [ABSTRACT FROM AUTHOR]

In this study, the gas–liquid two phase flow behavior in the vacuum vessel during the Rheinstahl-Heraeus (RH) refining process was investigated to improve the refining effect. Special attention is paid to investigate double powder injection lances system which is used to improve the refining efficiency during RH refining process. The melt flow behavior, circulation flow rate and mean residence time of the tracers with different powder injection gas flow rates and different configurations of the double powder injection lances are simulated using three-dimension numerical model based on Eulerian-Eulerian approach. The results show that, with the increasing gas flow rate of the power injection, the circulating flow rate and the mean residence time of tracer increases. It is also noted that the mean residence time of tracer varies with the different positions of the powder injection lances. It is found that there is an optimum location of the positions of the powder injection lances corresponding to the increasing of the residence time of powder and can improve the refining effect. [ABSTRACT FROM AUTHOR]

The problems of assessing the effectiveness of packed mass-transfer devices in relation to distillation processes have been considered. The authors have shown that the existing dependences of determining the height equivalent to a theoretical plate cannot be used to calculate tray columns and columns with vortex packings, the contact surfaces of the phases and coefficients of mass transfer of which depend substantially on the water concentration (reflux ratio) and gas rate (vapor for distillation). [ABSTRACT FROM AUTHOR]

This paper presents a fast, reliable multi-objective history-matching method based on proxy modeling to forecast the production performances of shale gas reservoirs for which all available post-hydraulic-fracturing production data, i.e., the daily gas rate and cumulative-production volume until the given date, are honored. The developed workflow consists of distance-based generalized sensitivity analysis (DGSA) to determine the spatiotemporal-parameter significance, fast marching method (FMM) as a proxy model, and a multi-objective evolutionary algorithm to integrate the dynamic data. The model validation confirms that the FMM is a sound surrogate model working within an error of approximately 2% for the estimated ultimate recovery (EUR), and it is 11 times faster than a full-reservoir simulation. The predictive accuracy on future production after matching 1.5-year production histories is assessed to examine the applicability of the proposed method. The DGSA determines the effective parameters with respect to the gas rate and the cumulative volume, including fracture permeability, fracture half-length, enhanced permeability in the stimulated reservoir volume, and average post-fracturing porosity. A comparison of the prediction accuracy for single-objective optimization shows that the proposed method accurately estimates the recoverable volume as well as the production profiles to within an error of 0.5%, while the single-objective consideration reveals the scale-dependency problem with lesser accuracy. The results of this study are useful to overcome the time-consuming effort of using a multi-objective evolutionary algorithm and full-scale reservoir simulation as well as to conduct a more-realistic prediction of the shale gas reserves and the corresponding production performances. [ABSTRACT FROM AUTHOR]

This paper presents the results of tests performed to study the effect of slurry solids concentration on the behavior of gas dispersion in industrial-scale mechanical flotation cells. The experiments were conducted at five concentrator facilities run by a Mexican mining company, specifically in the rougher bank of the lead/zinc flotation circuits. Those mechanical cells having significant contribution to the performance of the circuit, that is, the cells that enable high recovery, were characterized. The measurement protocol enables measurement of the superficial gas velocity, gas holdup and bubble size, and sampling of the mineral slurry. The measured data indicate that bubble size and gas holdup decreases as the concentration of solids increases. [ABSTRACT FROM AUTHOR]

In a flotation cell, bubble size is a function of both coalescence and breakup phenomena. Two phase tests, conducted in a conventional 5.5 L Denver mechanical flotation cell, studied the effect of impeller speed, gas flow rate and frother concentration on bubble size in various electrolyte-frother solutions. The addition of frother to a synthetic sea salt did reduce the measured bubble size (at certain mechanical conditions); whereas the effect of frother addition to NaCl was too small (when compared to measurement errors) to make significant conclusions. This led to more detailed CCC curves (0–50 ppm MIBC) for NaCl, NaCl + MgCl 2 , NaCl + CaSO 4 , and NaCl + KCl solutions, at constant electrolyte concentrations, to be conducted. They showed an increase in bubble size with the addition of MIBC. This was attributed to the saturation of frother at the air-water interface, reducing local surface tension gradients that help produce smaller bubbles. This occurrence is typically masked in traditional CCC curves due to the dominance of coalescence effects at low frother concentrations. [ABSTRACT FROM AUTHOR]

A novel experiment on gas flow in a cluster of combined tight cores was designed to study the degree of reserve recovery of tight gas reservoirs. The composition of the experimental apparatuses and the function of each apparatus are described in detail. An important apparatus was a clamping device that was 50 cm in length. Five pressure gauges were distributed at five different positions on the clamping device to monitor the gas flow pressure. Ten basic operation steps and a formula to determine pressure depletion degree are provided. We conducted 7 experiments using 30 core specimens and real natural gas collected from a tight reservoir in the Ordos basin of China. We categorized the specimens into three groups and designed low, middle and high water saturations and gas flow rates to study the influences of the physical properties, water saturation and gas rate on the degree of reserve recovery. We plotted dynamic pressure curves and calculated the pressure depletion degree, which quantitatively reflected the degree of reserve recovery of the example reservoir. We comparatively analysed the pressure depletion characteristics among different measurement points and experimental conditions. The research results showed that our designed experiment was useful and valuable. [ABSTRACT FROM AUTHOR]

Liquid loading is a major limiting production factor for maturing gas wells, whereas the modeling of liquid loading behavior is still quite immature and the prediction of the critical gas rate is not very reliable. On the basis of Turner's model, a new approach for calculating the critical gas flow rate is introduced in this paper, which takes into account the liquid amount in addition to the deformation and size of the liquid droplets. A dimensionless parameter is introduced in the new model to account for the deformation, distribution and maximum size of the liquid droplets. Well data from Turner's paper and Li Min's paper are used to validate the model. The prediction results agree well with both of the data. [ABSTRACT FROM AUTHOR]

In drillstem testing (DST), analyses of transient data are generally restricted to the post-cleanup period because rates often go unmonitored at early times during the cleanup phase, unless aided by multiphase flow metering. The value of early-time production data monitoring may be overlooked for two reasons: first, transients may be difficult to interpret because of two-phase flow in the formation; second, two-phase flow metering becomes a requirement. The objective of this study is two-fold: to estimate rate from multipoint-temperature sensor (MTS) data available for downhole telemetry with a rigorous transient analytical model, and to show the possible use of the computed rates to perform transient analysis for both the pre- and post-cleanup periods. Comparing and contrasting permeability estimates from the two periods provides guidance on the suitability of this approach. To that end, this study compares and contrasts rate computation with analytical methods. The new methods entail transient-temperature modeling with and without superposition effects. Two field examples strengthened the new rate-computation methods introduced here, and simulated examples probed the possibility of extracting meaningful information from the cleanup data. [ABSTRACT FROM AUTHOR]

Natural gas is an extremely vital supply of energy. Compared to other fossil fuels, demand for natural gas is experiencing a considerable growth due to its accessibility, availability, versatility and smaller environmental footprint. Glycol dehydration is the most common and economic method of water removal from natural gas streams. The water content of the dehydrated gas depends primarily on the lean triethylene glycol (TEG) concentration. Injecting stripping gas into the reboiler is taken into account as an effective way to improve the glycol concentration. In this article, two intelligent approaches including multilayer perceptron (MLP) neural network and least squares support vector machine (LSSVM) algorithm are utilized to predict optimum stripping gas flow rate in natural gas dehydration systems. Furthermore, a simple mathematical tool is presented for the application of interest. Based on the statistical analysis, an excellent match is noticed between the values obtained from the predictive tools (e.g., MLP, LSSVM and the empirical equations) and the real data so that the average absolute relative deviation percent (AARD %) is determined to be lower than 0.01%. [ABSTRACT FROM AUTHOR]

This paper proposes an alternative input-output (IO) price model in which all sectors of the economy are divided into two groups: (1) endogenous non-energy sectors; (2) exogenous but interrelated energy sectors. Using the latest IO table (2009-2010) of the Australian economy, we then used the proposed model to assess the impacts of an increase in 4 different energy prices (i.e. Oil and Gas Extraction; Petroleum and Coal Products; Electricity; and Utility Gas) on production costs of 110 non-energy sectors. We found that energy price rises will increase the production costs in tradable, less-labour intensive manufacturing sectors (such as basic chemical; electricity transmission, distribution; glass and glass products) as well as transport (road; air and space; water and road) and agricultural sub-industries (i.e. forestry; fishing; sheep, grains, dairy, cattle; logging) more than the other sectors. As expected, the service industries were least affected by energy price shocks. The effects of a rise in the prices of Electricity and Utility Gas on production cost of non-energy sectors are significantly less than those of two upstream energy sources (i.e. Oil and Gas Extraction; Petroleum and Coal products). [ABSTRACT FROM AUTHOR]

An adjoint formulation for the gradient-based optimization of oil-gas compositional reservoir simulation problems is presented. The method is implemented within an automatic differentiation-based compositional flow simulator (Stanford's Automatic Differentiation-based General Purpose Research Simulator, AD-GPRS). The development of adjoint procedures for general compositional problems is much more challenging than for oil-water problems due to the increased complexity of the code and the underlying physics. The treatment of nonlinear constraints, an example of which is a maximum gas rate specification in injection or production wells, when the control variables are well bottom-hole pressures, poses a particular challenge. Two approaches for handling these constraints are presented-a formal treatment within the optimizer and a simpler heuristic treatment in the forward model. The relationship between discrete and continuous adjoint formulations is also elucidated. Results for four example cases of increasing complexity are presented. Improvements in the objective function (cumulative oil produced) relative to reference solutions range from 4.2 to 11.6 %. The heuristic treatment of nonlinear constraints is shown to offer a cost-effective means for obtaining feasible solutions, which are, in some cases, better than those obtained using the formal constraint handling procedure. [ABSTRACT FROM AUTHOR]

A simple and effective method of the gas rate prediction from temperature and pressure data is discussed in this paper. Solving the inverse problem allows determination of the flow rate by matching the gas pressure and temperature distributions with measured profiles. Results of field data treatment show good agreement with the model prediction. [ABSTRACT FROM AUTHOR]

This article discusses the optimization of a petroleum production allocation problem through a parallel Dantzig-Wolfe algorithm. Petroleum production allocation problems are problems in which the determination of optimal production rates, lift gas rates and well connections are the central decisions. The motivation for modelling and solving such optimization problems stems from the value that lies in an increased production rate and the current lack of integrated software that considers petroleum production systems as a whole. Through our computational study, which is based on realistic production data from the Troll West field, we show the increase in computational efficiency that a parallel Dantzig-Wolfe algorithm offers. In addition, we show that previously implemented standard parallel algorithms lead to an inefficient use of parallel resources. A more advanced parallel algorithm is therefore developed to improve efficiency, making it possible to scale the algorithm by adding more CPUs and thus approach a reasonable solution time for realistic-sized problems. [ABSTRACT FROM AUTHOR]

The article offers information on the American Water Works Association's (AWWA) Manual M1, the Principles of Water Rates, Fees, and Charges, which serves as basis for water utilities to align rates for the recovery over the cost of service. It also describes the typical rate structure for natural gas and water utilities which consists a customer charge and a charge per unit of consumption. It also highlights the idea and practice of decoupling fixed charges from volume of usage.

The article discusses a study which explained the multiphase-flow mechanism used for gas-well liquid loading. The researchers found that liquid-loading observations were more compatible with film-flow reversal compared to the droplet-flow reversal. They also evaluated the benefits of different types of tubing-wall modification where hydrophobic coating reduces the gas rate by 50% during liquid loading.

Abstract: Currently, there are 14 gasification power plants in Thailand with a total capacity of 5.4 MWe., as of today DEDE invested in 7 plants each with a capacity range of 20 - 400 kWe and investment cost about 8,000 - 100,000 baht/kWe. Furthermore, another 4 pilot plants were installed in the Universities such as Naresuan University, Prince Songkhla University, Rajamangala University of Technology Thanyaburi, and Suranaree University of Technology. The investment cost of the thermal gasification plants is relatively high, ranging between 8,000 - 100,000 baht/kW, because most of plants are under technology improvement for cost reduction. If technology is stable, the investment cost will be able to reduce about 1,000 baht/kW. The 10 gasification power plants are strongly examined in this investigation. It was found that most of plants have a series problem of the inability of control gas production system for both producer gas rate and gas composition resulting from the lack of a good design system for feeding system and tar content removal. In order to develop gasification plants in Thailand, the research in this area must be continuous requirement for ensuring system stability resulting in cheaper investment cost [Copyright &y& Elsevier]

This article presents a concept of critical thickness in low permeable coalbed methane reservoirs with a simulation study when a horizontal well is used. The equations proposed to finish the simulation study are based on the Langmuir equation, Fick pseudo-steady state law, and Darcy equation, in which equivalent radius model and function of pseudo pressure are combined to consider the effect of diffusivity and compressibility. The method of finite difference is presented to solve the equations. Then we established the partial differential equations and the definite conditions that describe the mechanism of coal gas and water flow. As the low permeable property of a coal bed in China, we discussed the applicability of a horizontal well according to the reservoir thickness. The significant results from our study include: (1) There is critical reservoir thickness in developing low permeable coalbed methane reservoir with horizontal well. (2) When the thickness is less than the critical value, the cumulative gas production will be lower and the commercial efficiency is unsatisfactory. When the value is more than the critical one, the productivity will not increase as quickly as the reservoir thickness. On the contrary, it will be almost stable along with the reservoir thickness increase. (3) The production effect of the horizontal well on a low permeable coalbed methane reservoir will be decreased when the reservoir thickness is too high. (4) The peak gas rate will go down first and move upward later as the reservoir thickness increases. Consequently, the adaptability of the horizontal well to a low permeable coalbed methane reservoir should be analyzed first according to the reservoir thickness. [ABSTRACT FROM AUTHOR]

This article presents a numerical approach for the profit maximization by allocating an optimal injected gas in a continuous gas lift system. A performance curve of gas lift was designed that takes into account both lift and cycle efficiency. Piecewise cubic hermit interpolating polynomial is performed as a tool of interpolation to achieve a minimum error and a quantitative evaluation. A robust economic function and simulate annealing are integrated to determine the independence of decision variables and lift-gas rate, which yields a maximum profit. The model applied for a mature oil field reveals that the volume of injected gas reduces significantly by 63% and the revenue increases up to 13% compared with a conventional production optimization. The developed model will be applicable enough to enhance the profit in continuous gas life system. [ABSTRACT FROM AUTHOR]

In this study, a comprehensive laboratory investigation was conducted for the recovery of heavy oil from a three-dimensional (3-D) physical model, packed with 18°API gravity crude oil, brine and crushed limestone. A total of 15 experiments were conducted using the 3-D physical model with 30 cm × 30 cm × 6 cm dimensions. Basically, water-alternating gas (WAG) process was used for recovering heavy oil. Three groups of well configurations were mainly used: (i) vertical injection and vertical production wells, (ii) vertical injection and horizontal production wells, and (iii) horizontal injection and horizontal production wells. Base experiments were run with water only and carbondioxide alone and optimum rates for WAG process were determined. In CO 2 injection experiments, vertical injection and horizontal production well configuration supplied a higher recovery (15.06% OOIP) than that of the others. Horizontal injection and horizontal production well configuration gave poor recovery with the same gas rate, while vertical injection and vertical production was better off with a lower gas rate. The volumetric ratio of the water and CO 2 slugs (WAG ratio) was varied 1:3 to 1:10 in order to determine optimum conditions. For water alternating gas injection case at a WAG ratio 1:7, vertical injection and vertical production well configuration gave the highest recovery (21.04% OOIP). Waterflooding reached the best recovery (37.20% OOIP) in vertical injection and vertical production well configuration. Oil production from WAG injection is higher than that obtained from the injection of continuous CO 2 or waterflooding alone. [ABSTRACT FROM AUTHOR]

Abstract: This study was an investigation of the role of important parameters influencing pyrolysis yields from soybean cake. Experiments were carried out at temperatures ranging from 400 to 700°C, for various nitrogen flow rates, heating rates and particle sizes. The maximum liquid yield was 42.83% at a pyrolysis temperature of 550°C with a sweeping gas rate of 200cm3 min−1 and heating rate of 700°Cmin−1 for a soybean cake sample having 0.425< D p <0.85mm particle size. The various characteristics of liquid product were identified. Thus, the aliphatic sub-fraction of the bio-oil was analysed by GC-MS and further structural analyses of bio-oil and aromatic and polar sub-fractions were conducted using FT-IR and 1H-NMR. The H/C ratios and the structural analysis of the fractions obtained from the biocrudes showed that the fractions were quite similar to currently utilised transport fuels. [Copyright &y& Elsevier]

Abstract: Flotation cells have an operating gas rate range. A method to define the range objectively using the relationship between gas holdup and gas rate (ε g vs. J g) is introduced. This is made tractable by the necessary sensors becoming available. Examples in three cell types at three plants illustrate the procedure. [Copyright &y& Elsevier]

The article discusses the key findings of a Federal Energy Regulatory Commission (FERC) Initial Decision in a complaint proceeding against the Kinder Morgan subsidiary SFPP LP (SFPP), and its implications for oil pipeline rate-making. Practitioners of FERC natural gas pipeline and electric transmission rate-making may find the oil pipeline methodology of interest as it provides an alternative rate-making paradigm for consideration. As compared with the traditional depreciated original cost (DOC) rate base methodology, FERC adopted an alternative method for regulating oil pipelines called trended original cost (TOC).

The article discusses the Standard Market Design rule-making proposal issued by the U.S. Federal Energy Regulatory Commission, especially as it relates to the natural gas industry. The rule requires all electric transmission systems to be independently administered and use an open-access protocol for all transactions. Beyond that, it establishes independence requirements for regional transmission operators and independent transmission providers. One consequence of the rule is that the retail price of electricity, less the cost of electric transmission or natural gas transportation, should dictate the price of natural gas at production area centers.

Natural gas company managers concerned with customer satisfaction attempt to minimize the occurrence of extreme bills. Previously, only price fluctuations were addressed with derivative instruments; exchange-traded weather derivatives present a means of hedging exposure to increases in quantity of gas demanded during colder than expected winter months. We model a natural gas company's ability to adjust for consumer sensitivity and exposure to extreme bills with the use of an optimal mix of weather derivatives and gas pricing derivatives. We find consumer exposure to extreme bills is minimized when the utility uses pricing and weather derivatives. [ABSTRACT FROM AUTHOR]

We examine the applicability of price-cap mechanisms to the regulation of gas distribution company rates for gas supply and transportation services. Although distribution companies will continue to be regulated for the foreseeable future, we argue that a hybrid of price and profit regulation of transportation rates will increase allocative efficiency and provide greater incentives for productive efficiency. The design of incentives for cost minimization in long-term gas supply contracts is more challenging, but an index cap, based on the cost of gas acquired by other distribution companies, merits attention. [ABSTRACT FROM AUTHOR]

Focuses on the need of the natural gas and electric utility industries in the U.S. to develop new product pricing strategy due to increased competition. Limitations of traditional methods for product development and pricing; Determinants of effective product pricing; Ramifications of value attributes on product pricing; Issues that should be included in the utility's consideration of competitive position.

Discusses the alternatives to traditional cost-of-service rate-making offered by the U.S. Federal Energy Regulatory Commission to natural gas industry. Move of the commission to permit market-based rates for pipelines that demonstrate that they cannot exercise market power; Offer of the commission to permit incentive rates for pipelines that have market power; Decision of the commission to permit negotiated rates for pipelines that have market power.

Presents a forecast on the gas prices in the U.S. Anticipation for gas prices to retain its strength; Expectation for prices to trend higher into expiration; Elasticity of consumer demand for the goods; Detection of a minimal risk for oil price to collapse; Possibility for an increase in productive capacity.

The construction and application of mathematical models which aid in the determination of fair rates of return for regulated industries is a development of potentially great importance to both the theoretician and the purchaser of regulated industry services. This paper shows that the two apparently dissimilar models of fair rates of return under conditions of growth found in the literature are derivable from a third more general model of such a process. The relative usefulness of the models is discussed, along with the validity of the behavioral assumptions that underlie the models. [ABSTRACT FROM AUTHOR]

Delves into the implications of six-dollar gas on the gas industry and the consumers in the U.S. Offers of high gas production activities; Expansion of gas pipeline capacity; Evaluation of benefits and drawbacks posed on the natural gas market, gas customers and the gas industry.

Focuses on the incentive rate proposal submitted by BP Amoco PLC to the U.S. Federal Energy Regulatory Commission. Fundamental purpose of the proposal; Kinds of cost efficiencies that have been experienced in great measure in the exploration and production sector; Benefits of the proposal for gas companies and pipelines.

Focuses on the issues on the proposal for deregulating short-term pipeline capacity market in the U.S. Lifting of the price cap on local distribution companies capacity release transactions; Problems or deficiencies aimed on the proposal of the Federal Energy Regulatory Commission; Terms and conditions on the use of capacity auctions for all short-term sales.

Provides information on the resolution filed by the American Gas Association and the Interstate Natural Gas Association of America for negotiated pipeline terms and the U.S. Federal Energy Regulatory Commission's rate-making scheme. Idea of the proposal; Pitfalls of the resolution; Benefits of rate regulation.

Analyzes the impact of the U.S. Federal Energy Regulatory Commission's decision on complaints against interconnection charge by Southern California Gas Co. on local distribution companies (LDC) offering state-regulated intrastate service. Facts of the case; Basis of the decision of the commission; Possibility that LDCs will be subject to dual regulation.

Features comments of the author on the move of the U.S. Federal Energy Regulatory Commission to allow negotiated alternatives to natural gas companies. Question of the author on a part of the policy regarding the exposure of every negotiated deal to the general public; Reservations of the industry on the policy; Discussion of the content of the policy.