History-matching and forecasting tight/shale gas condensate wells using combined analytical, semi-analytical, and empirical methods
基于组合分析、半解析及实证方法的致密页岩气凝析井的历史拟合与预测
Journal of Natural Gas Science and Engineering, In Press, Corrected Proof, Available online 30 March 2015
Abstract: The primary focus of the majority of current, and foreseeable, natural gas drilling within North America is low-permeability liquid-rich gas and gas condensate reservoirs, where the liquid fraction is now a major source of revenue. Development of these liquid-rich resources is aided by the use of multi-fractured horizontal wells (MFHWs), and is at an early stage; further research is required to appropriately manage the resource for optimal hydrocarbon recovery.
The appropriate forecasting methodologies to apply to these tight liquid-rich plays are a focus of current research. While numerical simulation is the most rigorous forecasting methodology, practitioners have turned to simple analytical and empirical methods because of their ease-of-use and requirement of less data. However, these analytical and empirical approaches have limitations that limit their applicability for unconventional resevoirs with complex reservoir, hydraulic fracture and fluid properties.
In this study, the workflow of Clarkson (2013b) is applied to address the limitations of existing empirical and analytical methods for forecasting MFHWs producing from liquid-rich tight gas/shale. The workflow calls for constraint of analytical models by linking inputs to rate-transient analysis-derived reservoir and hydraulic fracture properties, and constraining empirical model forecasts to be consistent with analytical model forecasts. In order to address the range in reservoir/fracture properties observed in shales, a suite of analytical models is proposed. Similarly, a suite of empirical methods is used, and the models yielding the most accurate matches to the analytical models are selected for forecasting. Lastly, in order to bridge the gap between analytical and empirical methods, the semi-analytical method introduced by Clarkson and Qanbari (2015), which has as its basis the contacted gas-in-place calculations of Agarwal (2010), is also used for forecasting.
An important contribution of this work is the demonstration of the applicability of the analytical and semi-analytical models used in this work for tight gas/shale gas condensate MFHWs exhibiting multi-phase flow in the reservoir. As demonstrated in this study using simulation cases, constant condensate gas ratios can occur for tight/shale gas condensate wells exhibiting transient linear flow and flowing at near constant flowing bottomhole pressure, even for relatively rich gas cases, rendering the single-phase forecasting methods useful for forecasting gas and condensate phases. The accuracy of these methods is tested using simulated cases, and practicality of the workflow demonstrated using an actual field example of a liquid-rich shale MFHW.
This study will be of interest to those petroleum engineers who are faced with forecasting a large number of liquid-rich shale wells, and desire methods that can be simply applied to constrain forecasts and improve accuracy.
A novel polygeneration process to co-produce ethylene and electricity from shale gas with zero CO2 emissions via methane oxidative coupling
采用甲烷氧化耦合法（二氧化碳零排放）页岩气共产乙烯与电力的新多联产工艺
Energy Conversion and Management, Volume 92, 1 March 2015, Pages 406-420
Abstract: A techno-economic analysis of a novel process to co-produce ethylene and electricity using a recently developed methane oxidative coupling catalyst is presented. Several design variants are considered, featuring the use of traditional gas turbines, chemical looping combustion, and 100% carbon dioxide capture. Mass and energy balance simulations were carried out using Aspen Plus simulations, and particle swarm optimization was used to determine the optimal process design under a variety of market scenarios. A custom model for the gas turbine section was used to ensure that the negative impacts of various cooling strategies were factored into the analysis. The results show that by synergistically co-producing power and ethylene using this catalyst, ethylene can be produced at costs close to traditional steam cracking methods with nearly zero carbon dioxide emissions, even when factoring in the relatively poor conversion and selectivity of the chosen catalyst.
Analysis of two Alternatives to Produce Ethylene from Shale Gas
两种页岩气制备乙烯方法分析
Computer Aided Chemical Engineering, Volume 37, 2015, Pages 485-490
Abstract: The recent discoveries of shale gas have caused a decrease in the price of natural gas, which has opened a window of opportunities for its use not only as a source of energy but also as a feedstock for the production of chemical products. In this work, the use of shale gas for the production of ethylene is analysed. Two methods, the Oxidative Coupling of Methane (OCM) and the Methanol to Olefins (MTO) process are considered. The OCM is a direct-conversion process in which methane is converted to ethylene using a catalytic reactor. The MTO is a process with several steps where methane has to be first converted to syngas and then to methanol. The product, crude methanol, is finally converted to ethylene. Based on process simulations, an assessment of economic, energy and environmental considerations for each process was carried out. The results show that the MTO process provides a better alternative for the production of ethylene using shale gas. A sensitivity analysis shows that the OCM process can only be profitable under low prices of shale gas and high prices of ethylene.
Considerations for the development of shale gas in the United Kingdom
英国页岩气开发之思考
Science of The Total Environment, Volumes 512–513, 15 April 2015, Pages 36-42
Abstract: The United States shale gas boom has precipitated global interest in the development of unconventional oil and gas resources. Recently, government ministers in the United Kingdom started granting licenses that will enable companies to begin initial exploration for shale gas. Meanwhile, concern is increasing among the scientific community about the potential impacts of shale gas and other types of unconventional natural gas development (UGD) on human health and the environment. Although significant data gaps remain, there has been a surge in the number of articles appearing in the scientific literature, nearly three-quarters of which has been published since the beginning of 2013. Important lessons can be drawn from the UGD experience in the United States. Here we explore these considerations and argue that shale gas development policies in the UK and elsewhere should be informed by empirical evidence generated on environmental, public health, and social risks. Additionally, policy decisions should take into account the measured effectiveness of harm reduction strategies as opposed to hypothetical scenarios and purported best practices that lack empirical support.
Profitability of shale gas drilling: A case study of the Fayetteville shale play
页岩气钻探的效益状况：Fayetteville页岩气田实例研究
Energy, Volume 81, 1 March 2015, Pages 382-393
Svetlana Ikonnikova, Gürcan Gülen, John Browning, Scott W. Tinker
Abstract: Discussion on shale gas production sustainability raises the question of shale gas well profitability. The study presents a well economics model incorporating key geologic and production features of shale gas. The model is used to demonstrate analytically how profitability of a well may change depending on completion and local geology. We show how wells with the same expected production may have different profitability and, vice versa, how wells with different production profiles may appear to be equally attractive.
These conclusions are demonstrated with the empirical analysis based on historical data for almost 4000 horizontal wells in the Fayetteville Shale Play, North Central Arkansas. We look at six productivity tiers across the play accounting for drilling cost variability related to the dramatic depth change (from <1500-ft to over 8000-ft) in the natural gas producing formation. The subdivision of the play into productivity tiers and depth zones accounts for intra-tier profitability variation and helps to explain historical drilling patterns and to predict future development patterns in the field as demonstrated for 2012 by Gülen et al.
Modeling of fault activation and seismicity by injection directly into a fault zone associated with hydraulic fracturing of shale-gas reservoirs
页岩气藏水力压裂直接注水断层带的断层活化与地震活动模拟
Journal of Petroleum Science and Engineering, Volume 127, March 2015, Pages 377-386
Abstract: We conducted three-dimensional coupled fluid-flow and geomechanical modeling of fault activation and seismicity associated with hydraulic fracturing stimulation of a shale-gas reservoir. We simulated a case in which a horizontal injection well intersects a steeply dipping fault, with hydraulic fracturing channeled within the fault, during a 3-h hydraulic fracturing stage. Consistent with field observations, the simulation results show that shale-gas hydraulic fracturing along faults does not likely induce seismic events that could be felt on the ground surface, but rather results in numerous small microseismic events, as well as aseismic deformations along with the fracture propagation. The calculated seismic moment magnitudes ranged from about −2.0 to 0.5, except for one case assuming a very brittle fault with low residual shear strength, for which the magnitude was 2.3, an event that would likely go unnoticed or might be barely felt by humans at its epicenter. The calculated moment magnitudes showed a dependency on injection depth and fault dip. We attribute such dependency to variation in shear stress on the fault plane and associated variation in stress drop upon reactivation. Our simulations showed that at the end of the 3-h injection, the rupture zone associated with tensile and shear failure extended to a maximum radius of about 200 m from the injection well. The results of this modeling study for steeply dipping faults at 1000 to 2500 m depth is in agreement with earlier studies and field observations showing that it is very unlikely that activation of a fault by shale-gas hydraulic fracturing at great depth (thousands of meters) could cause felt seismicity or create a new flow path (through fault rupture) that could reach shallow groundwater resources.
Shale Gas Exploitation– Economic Effects and Risks
页岩气开采 – 经济效益与风险
Procedia Economics and Finance, Volume 22, 2015, Pages 95-104
Abstract: The paper approaches the possible economic impact of the exploitation and turning to account shale gas resources, regarded from the perspective of other countries’ accomplished results. Also, the team studies social acceptability issues for the shale gas exploitation on international and national levels. Next, the environmental risks associated to high volume hydraulic fracturing and horizontal drilling for shale gas exploitation are reviewed.
Life Cycle Assessment of North American Shale Gases
北美页岩气生命周期评估
Proceedings of the 4th International Gas Processing Symposium, 2015, Pages 317-325
Abstract: We have conducted life cycle assessments (LCAs) of Marcellus and Barnett shale gases used as fuels for power generation. These gases are geologically and geographically distinct, with considerable variability in drilling, completion and processing operations. We find that their carbon and water footprints are consistent and about 50% lower than those of coal. Furthermore, we find that 1.4% - 1.7% of gross methane production is emitted. We conclude that substantial greenhouse gas reductions and water consumption may result from the replacement of coal-fired power generation with gas-fired power generation, regardless of the source of shale gas.
