Induced seismicity caused by underground fluid injection occurs because of pore pressure changes that lead to stress changes in the reservoir and the surrounding formations. Despite that noticeable seismic events from fluid injection is very rare, proper assessment of possible seismic events is important. The objective of this study is to develop numerical models that simulate stress changes, fault slips, and ground floor movements induced by underground fluids injection.
The numerical analysis process presented in this work consists of three steps. First, stress changes around the reservoir due to fluid injection are analyzed using a FEM-BEM (Finite Element Method - Boundary Element Method) coupled model. Secondly, the stability of faults located near the reservoir is evaluated using the displacement discontinuity method. Thirdly, elastic waves caused by the fault slip is simulated using a FEM model where seismic response on the surface are calculated. A field case study is also presented to demonstrate the applicability of the numerical model developed in this work.
The numerical analysis results indicate that stress concentration occurs around a boundary between the basement and sandstone beneath the reservoir. This affects the stability of existing faults in this region. As a result, when the fault is slipped, seismicity may be triggered. It is assumed that the slip is caused by stress changes in the faulted region as well as a pore pressure change in the fault, which is caused by volumetric strain changes of the fluid in the fault. A field case study based on wastewater injection in the Southwestern region of the United States where injection induced seismicity events have been recently reported, is also performed in this work. In this case study, the variation of rock strength is considered one of important factors in induced seismicity events.
The novelty of our model is the ability to quantitatively assess the risk of induced seismicity due to wastewater injection, which can be also applied to other applications such as CCS and underground gas storages. Moreover, conducting risk assessment by these numerical models can improve safety of underground fluid injection operations.
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.
Earthquake in Cushing, OK -- home to the largest oil storage facility in the world -- leads to further regulatory action on disposal wells in the area. Research and development firm Battelle is working on a new induced-seismicity study that aims to help wastewater disposal well operators in Ohio stay on the good side of state regulators. Industry regulators in Oklahoma have rolled out broad new restrictions on more than 600 disposal wells as part of the largest action of its kind taken in response to earthquakes. A surge in earthquakes tightly clustered in southern Kansas that followed the large increase in produced water injections prompted the state to cut the daily limits on disposal wells in that area to see if that will help solve the problem.
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.
Management of produced water is driving subtle yet potentially consequential changes in certain regions. By assessing these common elements, partial risk profiles for both conditions can be assessed. Stanford researchers have mapped local susceptibility to man-made earthquakes in Oklahoma and Kansas. The new model incorporates physical properties of the Earth’s subsurface and forecasts a decline in potentially damaging shaking through 2020. Stanford geoscientists have found a way to detect thousands of tiny tremors around hydraulic fracturing operations that could serve as predictors of eventual larger earthquakes.
Oklahoma regulators forced an oil and gas producer to reduce operations on a well used for disposing salt water following a large earthquake that set off a series of seismic activity in the state. Oklahoma is tightening its rules for hydraulic fracturing after studying a new cluster of earthquakes in one of the hottest US regions for drilling. 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.
Are fugitive releases of natural gas and flaring environmental concerns? Can these be ameliorated today and even better in the future? What Is All This Talk About Emissions? Emissions are in the air and in the headlines every day. With growing regulations around all types of air emissions, are there ways that industry can deploy technologies cost-effectively in the current environment?
Experimentation reveals that swellable nanogels increase their size faster than expected or produce aggregation leading to serious blocking problems at the sandface. This paper studies if the addition of a surfactant can help improve injectivity. If crude prices, rig counts, and tight oil production demonstrate a stronger upward trend in the months to come, US shale operators may find themselves with more produced water than they bargained for. Water production normally increases as fields mature, and two main ways exist to deal with the produced water. One is to dispose of the produced water into dedicated disposal wells.
The UK shale operator will move forward with fracturing and testing its second well at its Lancashire site despite strict constraints on induced seismicity that hampered fracturing work on its first well. UK’s first horizontal shale well has yielded positive results after an initial flow test. But further testing—and fracturing of a second well—will have to come amid a continuation of UK’s stringent regulations on induced seismicity. Small quantities of gas and water are flowing to the surface from the UK’s first horizontal shale well—just days after operator Cuadrilla paused injection work for a second time amid earthquakes. Cuadrilla has encountered its first bumps in the road while fracturing its Preston New Road shale gas well, with two quakes already temporarily halting injection operations.