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The Netherlands will reduce production of its Groningen gas field by 10% from October to limit the risk of earthquakes, the country’s economy minister said in a letter to parliament on 18 April. The Pawnee Nation filed a lawsuit on 3 March in tribal court in Oklahoma against 27 oil and gas producers, seeking damages for an earthquake they said was caused from man-made activity related to hydraulic fracturing.
Gas to Wire (GTW) is a concept which will aid the UK to meet their growing energy demand as, GTW will allow marginal and somewhat depleted gas fields to convert natural gas to electricity onsite, with the electricity exported via subsea power cables - the concept is not yet fully commercialised offshore. This paper initially discusses what is GTW and then investigates two separate cases: the first focuses on evaluating the viability of GTW for the Kumatage gas field which is 78 km close to shore (located in the Southern North Sea) (
A discussion is also included in GTW's potential to work in conjunction with renewable technologies, such as tying back to Hornsea Project Four which is an offshore windfarm currently under the preapplication stage by Ørsted (hornseaprojects, 2019). It will be approximately 65 km from the Yorkshire coast and will be close to the Theddlethorpe and Bacton gas terminals (National Grid, 2019). By doing so, the electricity produced from Kumatage would need to be exported via a power cable to the windfarm. This study also discusses GTWs compatibility with existing renewable technologies to reduce carbon dioxide (CO2) emissions. By combining the findings of this paper, a further review of the potential of GTWs ability to unlock more marginal and stranded assets and contributing to the security of future UK energy supply. What can also be explored further from this paper is multiphase flow in the reservoir to then be able to model GTW to other offshore gas fields in the SNS.
A multibillion dollar boom in petrochemical plants proposed along the US Gulf Coast could pump as much greenhouse gas into the air as 131 coal-fired power plants by 2030, according to a study released by researchers at The University of Texas. Concentrations of carbon dioxide in the atmosphere surged at a record-breaking speed in 2016 to the highest level in 800,000 years, according to the World Meteorological Organization's Greenhouse Gas Bulletin. The abrupt changes in the atmosphere witnessed in the past 70 years are without precedent. The Netherlands will reduce production of its Groningen gas field by 10% from October to limit the risk of earthquakes, the country’s economy minister said in a letter to parliament on 18 April.
To estimate Rt under a variety of different logging conditions and in different formations, a simple three-parameter, step-profile invasion model is often used. This model consists of a flushed zone of resistivity Rxo and a sharp boundary at diameter di, with the uninvaded zone of resistivity Rt. Three independent, borehole-corrected resistivity measurements with appropriately chosen depths of investigation contain enough information from the formation to reliably solve for Rt using this model. Measurements with the following features should be chosen: small, correctable borehole effects; similar vertical resolutions; and well-distributed radial depths of investigation--one reading as deep as practical, one very shallow reading, and one intermediate reading. In conductive muds, the Dual Laterolog (DLL) Resistivity– Rxo combination tool provides simultaneous measurements suitable for evaluating Rt, Rxo, and di. It should be said that the value of Rt in a given bed is an interpreted parameter, and is almost never measured. As long as the formation is invaded, assumptions about the invasion profile must be made to estimate Rt. Figure 1 shows the electrode array used for deep and shallow laterolog measurements (LLd and LLs, respectively). Both logs share the same electrodes and have the same current-beam thickness, but different focusing currents give them different depths of investigation. The measure current (I0) is emitted from the central A0 electrode, returning to an "infinitely distant" electrode, usually at the surface.
Resistivity logging is an important branch of well logging. Essentially, it is the recording, in uncased (or, recently, even cased) sections of a borehole, of the resistivities (or their reciprocals, the conductivities) of the subsurface formations, generally along with the spontaneous potentials (SPs) generated in the borehole. This recording is of immediate value for geological correlation of the strata and detection and quantitative evaluation of possibly productive horizons. The information derived from the logs may be supplemented by cores (whole core or sidewall samples of the formations taken from the wall of the hole). As will be explained later, several types of resistivity measuring systems are used that have been designed to obtain the greatest possible information under diverse conditions (e.g., induction devices, laterolog, microresistivity devices, and borehole-imaging devices). Many service companies offer resistivity-logging services, and most offer a Web-based catalog ...
The detection and quantification of horizontal-permeability anisotropy play a vital role in optimally placing geothermal wells in geothermal reservoirs and thereby maximizing the geothermal-energy recovery from a given geothermal-reservoir area. However, the study of permeability anisotropy within the horizontal plane has received less attention and often permeability anisotropy is neglected in view of simplification.
Our study show that the horizontal permeability anisotropy has been observed in nearly all geothermal doublets that have been tested so far in the Netherlands. The main objective of this work is to study the impacts of horizontal permeability anisotropy inferred from pressure-interference tests on geothermal-doublets performance.
A theoretical relation between the measured directional permeability and the elements of the permeability tensor are presented. In a case study, horizontal anisotropy has been detected and quantified using a pressure-transient analysis, interference test, and the knowledge of the reservoir geometry gained from the geological study. In addition, this work uses a detailed three-dimensional thermal reservoir simulator of a reservoir in the West Netherlands Basin to demonstrate the importance of considering permeability anisotropy in predicting the lifecycle, which is determined by the cold-temperature breakthrough of an existing doublet and in optimally designing the second doublet in the same licensed area.
It has been established that the areal permeability anisotropy plays an important role in the energy sweep efficiency and doublets placement. A correct arrangement between the permeability anisotropy direction and the placement of the wells leads to longer breakthrough time and increasing the heat sweep efficiency.
This work shows that the knowledge gained from the interference test and/or other experiments about the presence, direction, and scale of anisotropy can be used to adjust the reservoir model that can be further used to design and optimize geothermal doublets.
Reservoir compaction in depleting gas fields can cause seismicity, as has been observed in a dozen countries (Foulger
For a few gas reservoirs, the evolution of potential fault slippage is simulated using the commonly adopted Mohr-Coulomb failure criterion. This shows that fault criticality is expected for reservoirs that showed seismic as well as non-seismic behavior. Apparently, some characteristic property is missing to explain the difference in behavior.
Using published pressure histories for seismically active gas fields, the relation is shown between seismic magnitude and relative depletion. It appears that in many cases, the first induced earthquake is relatively strong which suggests substantial cohesion of the faults. It is plausible from the geological history that in non-seismic regions, fault cohesion is larger, so that slippage is inhibited.
A new methodology for a "Level 2" Seismic Hazard Assessment has been developed for a geothermal project. Geomechanical models were created to understand the thermo-mechanical effects in the lifetime of a specific geothermal operation. Two types of geomechanical models are used, a 3-D Mohr-Coulomb model using both a deterministic and a probabilistic methodology, and a 2-D elastoplastic finite element model, simulating the lifetime and the associated mechanical changes caused by the geothermal operation. The simulated results show that, under maximum production conditions, there is a 1% likelihood of induced seismicity. Using published correlations, the movement along a fault is used to calculate the maximum magnitude of the unlikely seismicity, projected to be the order of 1.5 to 2 M w . As a mitigation method, a Traffic Light System is proposed. This allows the geothermal operation to continue while staying within the expected safety margins.
Liu, Kui (State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development) | Dahi Taleghani, Arash (Sinopec Research Institute of Petroleum Engineering) | Gao, Deli (China University of Petroleum, Beijing)
Summary Casing failure in shale gas wells has seriously impacted production from Weiyuan and Changning fields in Sichuan Province, China. Apparently, interaction of hydraulic fractures with nearby faults causes fault slippage, which in some situations has led to well shearing. Hence, we propose a semianalytical model in this paper to estimate the length of slippage along the fault that is caused by pressurization of a fault intercepted by the hydraulic fracture. These calculations have been performed for different configurations of the fault with respect to the hydraulic fracture and principal stresses. Using the semianalytical model provided in this paper, two fault slippage cases are calculated to assess the casing failure in nearby wells. In one case study, the calculated results of the fault slippage are consistent with the scale of casing deformation in that well and a microseismic magnitude caused by fault slippage is calculated that is larger than the detected events. The presented model will provide a tool for a quick estimation of the magnitude of fault slippage upon intersection with a hydraulic fracture, to avoid potential casing failures and obtain a more reliable spacing selection in the wells intersecting faults. Introduction The shale gas revolution has increased natural-gas supply in the United States and is about to change the world energy map very soon. New technology developments in horizontal drilling and multistage hydraulic fracturing have played critical roles in this revolution. Hydraulic-fracturing treatments mostly take place in multiple stages as thousands of cubic meters of fracturing fluid are injected into the formation in each stage over the course of a few hours. However, a few incidents of fault reactivation as a result of hydraulic fracturing has attracted some attention recently (Wasantha and Konietzky 2016). Before the research on the fault slippage caused by hydraulic fracturing in the shale plays, many earthquakes caused by fluid injection were reported in the literature. The first well-documented earthquake, identified to be caused by fluid injection, occurred in 1960.
Chen, Rongqiang (Texas A&M University) | Xue, Xu (Texas A&M University) | Park, Jaeyoung (Texas A&M University) | Yao, Changqing (Texas A&M University) | Chen, Hongquan (Texas A&M University) | Datta-Gupta, Akhil (Texas A&M University) | King, Michael J. (Texas A&M University) | Hennings, Peter (University of Texas Bureau of Economic Geology) | Dommisse, Robin (University of Texas Bureau of Economic Geology)
A series of earthquakes was recorded along a mapped fault system near Azle, Texas, in 2013. To identify the mechanism of seismicity, geologic, production/injection, and seismicity data are gathered to build a detailed simulation model with coupled fluid flow and geomechanics to model fluid injection/production and the potential onset of seismicity. Sensitivity studies for a broad range of reservoir and geomechanical parameters are performed to identify the influential parameters for injection wellhead pressure and earthquake data. A Pareto-based multiobjective history matching is performed using these influential parameters. The calibrated results are used to identify the controlling mechanisms for seismicity in the Azle area, North Texas, and their relationship to hydrocarbon production and fluid injection in the vicinity.
Geomechanical interaction has a significant impact on seismicity in the Azle area. Unbalanced loading created by the difference in the net fluid injection and production on different sides of the fault seems to generate accumulation of plastic strain change, likely resulting in the onset of seismicity. Previous studies ignore fluid withdrawal from gas production. Thus, they seem to have significantly underestimated the fluid withdrawal rates, almost by an order of magnitude. The equivalent bottomhole-voidage fluid rate used in this study suggests a drop in history-matched reservoir pore pressure that is consistent with the observed tubinghead pressure trends. Pore pressure increases may not fully explain the seismicity near the Azle area. Instead, geomechanical effects and strain propagation to the basement appear to be the dominant mechanisms. The low fault cohesion and minimum effective horizontal stress obtained from history matching confirm that the faults must be near or at the critically stressed state before the initiation of fluid production/injection. A sensitivity analysis indicates that the minimum effective horizontal stress and fracture gradient play a critical role in the potential risk for seismicity related to fluid injection/production. A streamline flow pattern further shows that there is no fluid movement in the basement formation and the unbalanced loading from different sides of the fault is more likely the controlling mechanism for seismicity.