Pressure Front Research Articles

Explications des pressions de fluides transitoires à longue portée engendrées par le stockage d’eaux usées de champs pétrolifères à l’aide du principe de superposition hydrogéologique

Injection-induced earthquakes are now a regular occurrence across the midcontinent United States. This phenomenon is primarily caused by oilfield wastewater disposal into deep geologic formations, which induces fluid pressure transients that decrease effective stress and trigger earthquakes on critically stressed faults. It is now generally accepted that the cumulative effects of multiple injection wells may result in fluid pressure transients migrating 20–40 km from well clusters. However, one recent study found that oilfield wastewater volume and earthquake occurrence are spatially cross-correlated at length-scales exceeding 100 km across Oklahoma. Moreover, researchers recently reported observations of increasing fluid pressure in wells located ~90 km north of the regionally expansive oilfield wastewater disposal operations at the Oklahoma-Kansas border. Thus, injection-induced fluid pressure transients may travel much longer distances than previously considered possible. This study utilizes numerical simulation to demonstrate how the hydrogeologic principle of superposition reasonably explains the occurrence of long-range pressure transients during oilfield wastewater disposal. The principle of superposition states that the cumulative effects of multiple pumping wells are additive and results from this study show that just nine high-rate injection wells drives a 10-kPa pressure front to radial distances exceeding 70 km after 10 years, regardless of basement permeability. These results yield compelling evidence that superposition is a plausible mechanistic process to explain long-range pressure accumulation and earthquake-triggering in Oklahoma and Kansas.

A risk-based approach to evaluating the Area of Review and leakage risks at CO2 storage sites

The U.S. Environmental Protection Agency’s Class VI regulations for underground carbon dioxide (CO2) injection require owners and operators of storage projects to identify (1) an Area of Review (AoR) that represents the region that may be affected by the injection of CO2, and (2) leakage risks that might impact the quality of underground sources of drinking water (USDWs). This article describes how such risks can be determined by accounting for the physical and chemical properties of all components of a CO2 storage site using elements of the National Risk Assessment Partnership Integrated Assessment Model for Carbon Storage (NRAP-IAM-CS). We used practical data from three sites that are part of two CarbonSAFE (Carbon Storage Assurance Facility Enterprise) projects to demonstrate application of the NRAP-IAM-CS toolset to determine project risk areas.NRAP-IAM-CS was used to estimate the project risk area that could represent the AoR and the impact of leakage through legacy wells to overlying drinking waters at these candidate CO2 storage sites. Our study shows that risk to USDWs is minimal despite (1) the presence of multiple legacy wells at these sites where the AoR approximates the maximum extent of injected CO2 or (2) the presence of a much larger AoR approximating the pressure front caused by the injection of CO2.

Large-amplitude Quasiperiodic Pulsations as Evidence of Impulsive Heating in Hot Transient Loop Systems Detected in the EUV with SDO/AIA

Abstract Short heat pulses can trigger plasma pressure fronts inside closed magnetic tubes in the corona. The alternation of condensations and rarefactions from the pressure modes drive large-amplitude pulsations in the plasma emission. Here we show the detection of such pulsations along magnetic tubes that brighten transiently in the hot 94 Å EUV channel of the Solar Dynamics Observatory/AIA. The pulsations are consistent with those predicted by hydrodynamic loop modeling, and confirm pulsed heating in the loop system. The comparison of observations and model provides constraints on the heat deposition: a good agreement requires loop twisting and pulses deposited close to the footpoints with a duration of 0.5 minutes in one loop, and deposited in the corona with a duration of 2.5 minutes in another loop of the same loop system.

Convergence properties of detonation simulations

ABSTRACTWe present a high-resolution convergence study of detonation initiated by a temperature gradient in a stoichiometric hydrogen–oxygen mixture using the PENCIL CODE and compare with a code that employs a fifth order weighted essentially non-oscillating (WENO) scheme. With Mach numbers reaching 10–30, a certain amount of shock viscosity is needed in the PENCIL CODE to remove or reduce numerical pressure oscillations on the grid scale at the position of the shock. Detonation is found to occur for intermediate values of the shock viscosity parameter. At fixed values of this parameter, the numerical error associated with those small wiggles in the pressure profile is found to decrease with decreasing mesh width like down to . With the WENO scheme, solutions are smooth at , but no detonation is obtained for . This is argued to be an artifact of a decoupling between pressure and reaction fronts.

Comparison of pressure front with tracer front advance and principal flow regimes in hydraulically fractured wells in unconventional reservoirs

Pressure depletion patterns near hydraulically fractured wells in ultra-low permeability reservoirs occupy a much larger region than outlined by fluid withdrawal contours. When used for reservoirs with moderate or high permeability (say k > 1 mD), industry never needed to caution using pressure depletion plots as a proxy for fluid removal or drained rock volume (DRV). For such conventional reservoirs, pressure depletion plots are good proxies for fluid removal or drained rock volume (DRV). The fluid that moves from the margins of a pressure front, indicative of the so-called diffusive depth of investigation (DOI), will reach the well on the time-scale of economic life of the well. However, a whole new way of thinking is required when studying ultra-low permeability shales (nanoDarcy range), where the distinction between pressure depletion zones and the DRV regions (where fluid is recovered from) becomes crucial to understand which factors control the hydrocarbon recovery process. Our detailed analysis compares the diffusive DOI, of the leading edge of the pressure depletion front, and that of the convective DRV given by a tracer front. Results show that the pressure depletion front between the fractures quickly approaches the adjoining fracture pressure, and most of the production originates from the fracture tips after 12 months. The pressure depletion pattern vastly overestimates the DRV, whereas the tracer front shows the actual produced rock volume. A final section evaluates the specific flow regimes that correspond to certain diffusive DOI and convective DRV growth stages in the life of the well. The discussion section explains how production diagnostic plots can be used to identify the moment in the well life when enhanced oil recovery methods should be applied. This study can facilitate a better understanding of the fluid flow in fractured porous media and can be used to optimize fracture and well spacing to maximize the DRV.

High density oilfield wastewater disposal causes deeper, stronger, and more persistent earthquakes

Oilfield wastewater disposal causes fluid pressure transients that induce earthquakes. Here we show that, in addition to pressure transients related to pumping, there are pressure transients caused by density differences between the wastewater and host rock fluids. In northern Oklahoma, this effect caused earthquakes to migrate downward at ~0.5 km per year during a period of high-rate injections. Following substantial injection rate reductions, the downward earthquake migration rate slowed to ~0.1 km per year. Our model of this scenario shows that the density-driven pressure front migrates downward at comparable rates. This effect may locally increase fluid pressure below injection wells for 10+ years after substantial injection rate reductions. We also show that in north-central Oklahoma the relative proportion of high-magnitude earthquakes increases at 8+ km depth. Thus, our study implies that, following injection rate reductions, the frequency of high-magnitude earthquakes may decay more slowly than the overall earthquake rate.

Behavior of Low-Velocity Detonation in Stoichiometric Mixture of Ammonium Perchlorate and Polymethyl Methacrylate

Low-velocity detonation in mixtures of ammonium perchlorate and fuel additives in high relative density charges is an interesting subject for the scientific research, with potential for practical applications in pulse nozzle and projective setups. However, information about the process is scanty and mainly concerns the measurements of the wave propagation velocities. This paper describes the results of a research aimed at obtaining the data base on properties and behavior of low-velocity detonation (LVD) in pressed charges of the mixture of ammonium perchlorate and 15% polymethyl methacrylate. The firings have been fulfilled at the pulse laboratory projectile setup and the strong steel confinements equipped with the nozzle block or a projectile with the process initiated by a booster produced from RDX or the TNT/RDX 30/70 mixture. The thrust impulse, trajectory of the projectile, pressure, and LVD wave front trajectory have been recorded. According to the measurement results, the muzzle velocity, the pressure at the projectile, and the burning completeness of the mixture have been calculated. In the experiments, the relative charge density has varied from 0.85 to 0.96, the ammonium perchlorate particle size has been from 20 to 200 μm, and the charge length and the projectile mass have varied as well. The experiments were supplemented with numerical simulation. Emphasis was lain on the interaction of a low-velocity detonation wave with end rarefaction waves. The conditions under which the high completeness of chemical conversion of the mixture can be reached with the acceptable level of the maximum pressure (1–1.5 GPa) are considered.

Improving pressure-limited CO2 storage capacity in saline formations by means of brine extraction

The carbon dioxide (CO2) storage capacity of saline formations may be constrained by reservoir pressure limitations. Brine extraction could be necessary to increase the CO2 storage capacity of a given formation, manage the extent of the underground CO2 plume and induced pressure front, and control the migration direction. To estimate the additional CO2 storage capacity of a saline formation that can be made accessible by extraction of in-situ brines, a three-dimensional (3D) generic cubic cell containing one CO2 injector in the middle surrounded by four brine extractors at each corner of the cell was assumed. A series of Tough2-ECO2N reservoir simulations were constructed with varying reservoir properties and run. Based on a series of scenarios, a mechanism was developed and demonstrated that resulted in derivation of a function to provide estimates of the ratio of total CO2 injection over the brine extraction rate for a given scenario. We selected multiple saline formations in U.S. basins and evaluated the potential to increase the combined dynamic CO2 storage capacity of the selected saline formations to over 1000 million metric tonnes per year (Mt/yr) of CO2 for 100 years by means of brine extraction. Such storage capacities may be adequate to accommodate the CO2 injection rates suggested for the United States under a “beyond two-degree Celsius scenario” (B2DS) that has been proposed to maintain global temperature rise to less than 2°C above pre-industrial reported levels. The results suggest that B2DS goals could be achieved with a volume ratio of brine extraction to CO2 injection as low as 1:4, which is far lower than the ratios that have been commonly assumed in the literature.

Safety and Reduction of Technology-Related Risks in the Process of Earth Dams’ and Dams’ Operation

Ground water-retaining structures belong to hydrodynamically dangerous objects, most of the accidents are due to errors made during the design, construction and operation of structures, including insufficient ridge stock above the water level in the reservoir.The reason of the pressure front breakthroughs of three hundred dams in various countries of the world for 175 years was the overflow of water through the ridge of the dam (35% of cases).The article provides the tasks for improving, creating more effective technological and constructive measures to combat defects and damages of ground water retaining structures based on known, positively proven and improved technologies and technological processes that take into account the technological and financial capabilities of local repair and construction organizations and farms having machines and mechanisms and local raw material base at their disposal.

Organization of Embryonic Morphogenesis via Mechanical Information

Embryonic organizers establish gradients of diffusible signaling molecules to pattern the surrounding cells. Here, we elucidate an additional mechanism of embryonic organizers that is a secondary consequence of morphogen signaling. Using pharmacological and localized transgenic perturbations, 4D imaging of the zebrafish embryo, systematic analysis of cell motion, and computational modeling, we findthat the vertebrate tail organizer orchestrates morphogenesis over distances beyond the range of morphogen signaling. The organizer regulates the rate and coherence of cell motion in the elongating embryo using mechanical information that is transmitted via relay between neighboring cells. This mechanism is similar to a pressure front in granular media and other jammed systems, but in the embryo the mechanical information emerges from self-propelled cell movement and not force transfer between cells. The propagation likely relies upon local biochemical signaling that affects cell contractility, cell adhesion, and/or cell polarity but is independent of transcription and translation.

A Magnetic Pressure Front Upstream of the Heliopause and the Heliosheath Magnetic Fields and Plasma, Observed during 2017

Abstract Voyager 1 (V1), moving in the interstellar magnetic field, observed an increase in the daily averages of B beginning on day ≈346, 2016, rising to a local maximum on day ≈382, and declining nearly monotonically for the most part until day 720, measured from 2016.0. A pressure front was observed during a ≈35-day interval beginning on day 346, 2016. The pressure front observed by V1 was not a shock, although one might expect it to evolve into a shock. Voyager 2 (V2) observed the distant heliosheath during 2017. The average B in the heliosheath was relatively high, 0.130 nT. The distribution of azimuthal angles had two nearly equal maxima at approximately 90° and 180°. An unusual transition of the BT component from a large “away” sector to a large “toward” sector occurred during 2017 from day 101 to day 239. Abrupt but small changes in magnetic polarity occurred between day 146 and day 239, when the average BT component of B was close to zero. Changes in the >70 MeV nucleon−1 cosmic-ray intensity were qualitatively related to the B(t) profile described by the CR-B relationship. There was no net decrease in magnetic flux at V2 in the heliosheath during 2017 that might be attributed to ongoing magnetic reconnection in the heliosheath. Small-scale increments in B can be described by a q-Gaussian distribution with q = 1.64 ± 0.02 for hourly averages of B and q = 1.54 ± 0.08 for daily averages of B.

Full-field Ultrahigh-speed Quantification of Dynamic Shear Ruptures Using Digital Image Correlation

Producing dynamic ruptures in the laboratory allows us to study fundamental characteristics of interface dynamics. Our laboratory earthquake experimental setup has been successfully used to reproduce a number of dynamic rupture phenomena, including supershear transition, bimaterial effect, and pulse-like rupture propagation. However, previous diagnostics, based on photoelasticity and laser velocimeters, were not able to quantify the full-field behavior of dynamic ruptures and, as a consequence, many key rupture features remained obscure. Here we report on our dynamic full-field measurements of displacement, velocities, strains and strain rates associated with the spontaneous propagation of shear ruptures in the laboratory earthquake setup. These measurements are obtained by combining ultrahigh-speed photography with the digital image correlation (DIC) method, enhanced to capture displacement discontinuities. Images of dynamic shear ruptures are taken at 1-2 million frames/s over several sizes of the field of view and analyzed with DIC to produce a sequence of evolving full-field maps. The imaging area size is selected to either capture the rupture features in the far field or to focus on near-field structures, at an enhanced spatial resolution. Simultaneous velocimeter measurements on selected experiments verify the accuracy of the DIC measurements. Owing to the increased ability of our measurements to resolve the characteristic field structures of shear ruptures, we have recently been able to observe rupture dynamics at an unprecedented level of detail, including the formation of pressure and shear shock fronts in viscoelastic materials and the evolution of dynamic friction.

Propagation of Pulsed Pressure during Electrohydraulic Drilling

We have analyzed the propagation of pulsed pressure produced by electric discharges in a heterogeneous liquid during well drilling. The pressure dynamics has been calculated based on theoretical analysis of the nonlinear process of the electrohydraulic effect in a heterogeneous medium. As a result of analysis, the time dependences of the relative pressure and shock front coordinate have been obtained.

Fluid Pressure‐Triggered Foreshock Sequence of the 2008 Mogul Earthquake Sequence: Insights From Stress Inversion and Numerical Modeling

AbstractIn Mogul west of Reno, Nevada, USA, in late February 2008 an earthquake sequence occurred that culminated in a magnitude 4.9 mainshock after a foreshock‐rich period lasting approximately 2 months on previously unidentified fault structures. In this article, we show that the foreshock sequence may have been driven by a fluid pressure intrusion. We use 1,082 previously calculated earthquake focal mechanisms to infer the local stress field as well as 1,408 relocated foreshock events to determine the required excess fluid pressure field in the source region of the Mogul earthquake sequence to trigger these events. A model of nonlinear pore pressure diffusion is used to model the fluid flow in a highly fractured subsurface. We find a strong correlation between high fluid pressure fronts and foreshock hypocenters, suggesting a natural fluid‐driven earthquake sequence.

Распространения импульсного давления при электрогидравлическом бурении

AbstractWe have analyzed the propagation of pulsed pressure produced by electric discharges in a heterogeneous liquid during well drilling. The pressure dynamics has been calculated based on theoretical analysis of the nonlinear process of the electrohydraulic effect in a heterogeneous medium. As a result of analysis, the time dependences of the relative pressure and shock front coordinate have been obtained.

Effect of rainfall uncertainty on the performance of physically based rainfall–runoff models

AbstractThis paper analyses the effect of rain data uncertainty on the performance of two hydrological models with different spatial structures: a semidistributed and a fully distributed model. The study is performed on a small catchment of 19.6 km2 located in the north‐west of Spain, where the arrival of low pressure fronts from the Atlantic Ocean causes highly variable rainfall events. The rainfall fields in this catchment during a series of storm events are estimated using rainfall point measurements. The uncertainty of the estimated fields is quantified using a conditional simulation technique. Discharge and rain data, including the uncertainty of the estimated rainfall fields, are then used to calibrate and validate both hydrological models following the generalized likelihood uncertainty estimation (GLUE) methodology. In the storm events analysed, the two models show similar performance. In all cases, results show that the calibrated distribution of the input parameters narrows when the rain uncertainty is included in the analysis. Otherwise, when rain uncertainty is not considered, the calibration of the input parameters must account for all uncertainty in the rainfall–runoff transformation process. Also, in both models, the uncertainty of the predicted discharges increase in similar magnitude when the uncertainty of rainfall input increase.

Estimating the pressure-limited CO2 injection and storage capacity of the United States saline formations: Effect of the presence of hydrocarbon reservoirs

The U.S. Geological Survey (USGS) national assessment of carbon dioxide (CO2) storage capacity evaluated 192 saline Storage Assessment Units (SAUs) in 33 U.S. onshore sedimentary basins that may be utilized for CO2 storage (see USGS Circular 1386). Similar to many other available models, volumetric analysis was utilized to estimate the initial CO2 injection and storage capacity of these SAUs based on aquifer characteristics and buoyant and residual trapping. The factor being almost always overlooked in most CO2 storage capacity models is that many of the evaluated SAUs contain large numbers of both conventional and unconventional discovered and undiscovered oil and gas reservoirs. The hydrocarbon production and pressure distribution of the resident oil and gas reservoirs may be negatively influenced by the propagated CO2 plume and pressure front resulting from a CO2 injection and storage operation in the surrounding SAU.To have a more realistic and accurate estimation of CO2 injection and storage capacity in saline formations, a model was previously developed that considers the CO2 injectivity of a given formation, underground pressure build-up limitations imposed by the rock fracturing pressure and the presence of hydrocarbon reservoirs within these aquifers. The developed method estimates the pre–brine extraction, pressure-limited CO2 injection and storage capacity of a saline formation by applying 3D numerical simulation only on the effective injection area (Aeff) surrounding each CO2 injection well utilizing TOUGH2-ECO2N simulation software.

Avoiding confusion between pressure front pulse displacement and groundwater displacement: Illustration with the pumping test in a confined aquifer

AbstractTwo distinct phenomena may be distinguished and defined during a pumping test conducted in a confined aquifer: the pressure front pulse displacement and the groundwater displacement. This Scientific briefing examines and clarifies the difference between the pressure wave displacement and the groundwater displacement, by stating the differences in their respective transit times and velocities. The pressure front pulse displacement is controlled by the diffusivity of the aquifer, whereas groundwater displacement is controlled by the pumping flow rate and the effective porosity of the aquifer. To calculate the transit time and velocity of each type of displacement, several equations are presented and compared. An example is provided to illustrate the differences in velocity between the pressure front pulse displacement and the groundwater displacement.

Effect of water concentration on the shock response of polyethylene glycol diacrylate (PEGDA) hydrogels: A molecular dynamics study

Shockwave propagation in polyethylene glycol diacrylate (PEGDA) hydrogels is simulated for the first time using nonequilibrium molecular dynamics simulations. PEGDA hydrogel models are built using the “perfect network” approach such that each crosslink junction is comprised of six chain connections. The influence of PEGDA concentration (20–70 wt%) on shock behavior is investigated for a range of particle velocities (200–1000 m/s). In agreement with reported experimental results in the literature on gels with similar densities, shock velocity and pressure in PEGDA hydrogels are found to increase with polymer concentration, within a range bounded by pure water and pure polymer behaviors. Nonlinear relationships are observed for shock pressure and shock front thickness as a function of concentration, and a logarithmic equation is proposed to describe this behavior. In addition, the relationship between pressure and shock front thickness is compared with hydrodynamic theory. Deviation from hydrodynamic predictions is observed at high particle velocities and this deviation is found to be related to viscosity changes. A power-law relationship between strain rate and pressure in PEGDA hydrogels is identified, similar to that of metals. However, a power-law exponent of 1.4 is computed for all gel concentrations, whereas an exponent of 4 is typically reported for metals.

The Role of Fault-Zone Architectural Elements on Pore Pressure Propagation and Induced Seismicity.

We used hydrogeologic models to assess how fault-zone properties promote or inhibit the downward propagation of fluid overpressures from a basal reservoir injection well (150 m from fault zone, Q = 5000 m3 /day) into the underlying crystalline basement rocks. We varied the permeability of the fault-zone architectural components and a crystalline basement weathered layer as part of a numerical sensitivity study. Realistic conduit-barrier style fault zones effectively transmit elevated pore pressures associated with 4 years of continuous injection to depths of approximately 2.5 km within the crystalline basement while compartmentalizing fluid flow within the injection reservoir. The presence of a laterally continuous, relatively low-permeability altered/weathered basement horizon (kaltered layer = 0.1 × kbasement ) can limit the penetration depth of the pressure front to approximately 500 m. On the other hand, the presence of a discontinuous altered/weathered horizon that partially confines the injection reservoir without blocking the fault fluid conduit promotes downward propagation of pressures. Permeability enhancement via hydromechanical failure was found to increase the depth of early-time pressure front migration by a factor of 1.3 to 1.85. Dynamic permeability models may help explain seismicity at depths of greater than 10 km such as is observed within the Permian Basin, NM.