Applied Technologies and Prospects of Conformance Control Treatments in China

China is the largest user of chemical-based conformance control treatments and a series of technologies have been successfully developed and deployed in recent years. This paper first shows the milestones of development and application of conformance control technologies in China. Then integrated conformance control technologies are reviewed followed by the lessons we have learned, and then a few major specific conformance control technologies are addressed, including tracer injection and channels explanation, potentiometric testing to identify areal sweep efficiency, Pressure Index (PI) decisionmaking technology to select well candidate, complementary decision-making technology to select well candidate and design application parameters, and major chemicals for in-depth fluid diversion technologies. In addition, this paper also describes the principles and applications of some promising technologies of combined chemical-based conformance treatment with other EOR/IOR process, including the combination technology of surfactant and water shutoff, profile control and mini-scale surfactant flooding, acid treatment and profile control treatment. Finally, this paper summarizes the problems and challenges faced by mature water flooded oilfields in China. Based on recent well tests, tracer testing and interpretation, and previous water control treatment experience, it appears that channels or high permeability streaks are common in mature water flooded oilfields. Some research directions and promising technologies are suggested

Two regions of seafloor deformation generated the tsunami for the 13 November 2016, Kaikoura, New Zealand earthquake

The 13 November 2016 Kaikoura, New Zealand, M_w 7.8 earthquake ruptured multiple crustal faults in the transpressional Marlborough and North Canterbury tectonic domains of northeastern South Island. The Hikurangi trench and underthrust Pacific slab terminate in the region south of Kaikoura, as the subdution zone transitions to the Alpine fault strike-slip regime. It is difficult to establish whether any coseismic slip occurred on the megathrust from on-land observations. The rupture generated a tsunami well recorded at tide gauges along the eastern coasts and in Chatham Islands, including a ~4 m crest-to-trough signal at Kaikoura where coastal uplift was about 1 m, and at multiple gauges in Wellington Harbor. Iterative modeling of teleseismic body waves and the regional water-level recordings establishes that two regions of seafloor motion produced the tsunami, including an M_w ~7.6 rupture on the megathrust below Kaikoura and comparable size transpressional crustal faulting extending offshore near Cook Strait

Effects of dispersion in tsunami Green's functions and implications for joint inversion with seismic and geodetic data: a case study of the 2010 Mentawai M_W 7.8 earthquake

Tsunami observations play an important role in resolving offshore earthquake slip distributions. Nondispersive shallow-water models are often used with a static initial sea surface pulse derived from seafloor deformation in computation of tsunami Green's functions. We compare this conventional approach with more advanced techniques based on a dispersive model with a static initial sea surface pulse and with the surface waves generated from kinematic seafloor deformation. These three sets of tsunami Green's functions are implemented in finite-fault inversions with and without seismic and geodetic data for the 2010 Mentawai M_w 7.8 tsunami earthquake. Seafloor excitation and wave dispersion produce more spread-out waveforms in the Green's functions leading to larger slip with more compact distribution through the inversions. The fit to the recorded tsunami and the deduced seismic moment, which reflects the displaced water volume, are relatively insensitive to the approach used for computing Green's functions

The 2017 M_W 8.2 Chiapas, Mexico Earthquake: Energetic Slab Detachment

On 8 September 2017, a great (M_w 8.2) normal faulting earthquake ruptured within the subducting Cocos Plate ~70 km landward from the Middle American Trench beneath the Tehuantepec gap. Iterative inversion and modeling of teleseismic and tsunami data and prediction of GPS displacements indicate that the steeply dipping rupture extended ~180 km to the northwest along strike toward the Oaxaca coast and from ~30 to 70 km in depth, with peak slip of ~13 m. The rupture likely broke through the entire lithosphere of the young subducted slab in response to downdip slab pull. The plate boundary region between the trench and the fault intersection with the megathrust appears to be frictionally coupled, influencing location of the detachment. Comparisons of the broadband body wave magnitude (m_B) and moment-scaled radiated energy (E_R/M_0) establish that intraslab earthquakes tend to be more energetic than interplate events, accounting for strong ground shaking observed for the 2017 event

Surfactant Induced Reservoir Wettability Alteration: Recent Theoretical and Experimental Advances in Enhanced Oil Recovery

Reservoir wettability plays an important role in various oil recovery processes. The origin and evolution of reservoir wettability were critically reviewed to better understand the complexity of wettability due to interactions in crude oil-brine-rock system, with introduction of different wetting states and their influence on fluid distribution in pore spaces. The effect of wettability on oil recovery of waterflooding was then summarized from past and recent research to emphasize the importance of wettability in oil displacement by brine. The mechanism of wettability alteration by different surfactants in both carbonate and sandstone reservoirs was analyzed, concerning their distinct surface chemistry, and different interaction patterns of surfactants with components on rock surface. Other concerns such as the combined effect of wettability alteration and interfacial tension (IFT) reduction on the imbibition process was also taken into account. Generally, surfactant induced wettability alteration for enhanced oil recovery is still in the stage of laboratory investigation. The successful application of this technique relies on a comprehensive survey of target reservoir conditions, and could be expected especially in low permeability fractured reservoirs and forced imbibition process

The 2017 M_W 8.2 Chiapas, Mexico Earthquake: Energetic Slab Detachment

On 8 September 2017, a great (M_w 8.2) normal faulting earthquake ruptured within the subducting Cocos Plate ~70 km landward from the Middle American Trench beneath the Tehuantepec gap. Iterative inversion and modeling of teleseismic and tsunami data and prediction of GPS displacements indicate that the steeply dipping rupture extended ~180 km to the northwest along strike toward the Oaxaca coast and from ~30 to 70 km in depth, with peak slip of ~13 m. The rupture likely broke through the entire lithosphere of the young subducted slab in response to downdip slab pull. The plate boundary region between the trench and the fault intersection with the megathrust appears to be frictionally coupled, influencing location of the detachment. Comparisons of the broadband body wave magnitude (m_B) and moment-scaled radiated energy (E_R/M_0) establish that intraslab earthquakes tend to be more energetic than interplate events, accounting for strong ground shaking observed for the 2017 event

Effects of dispersion in tsunami Green's functions and implications for joint inversion with seismic and geodetic data: a case study of the 2010 Mentawai M_W 7.8 earthquake

Tsunami observations play an important role in resolving offshore earthquake slip distributions. Nondispersive shallow-water models are often used with a static initial sea surface pulse derived from seafloor deformation in computation of tsunami Green's functions. We compare this conventional approach with more advanced techniques based on a dispersive model with a static initial sea surface pulse and with the surface waves generated from kinematic seafloor deformation. These three sets of tsunami Green's functions are implemented in finite-fault inversions with and without seismic and geodetic data for the 2010 Mentawai M_w 7.8 tsunami earthquake. Seafloor excitation and wave dispersion produce more spread-out waveforms in the Green's functions leading to larger slip with more compact distribution through the inversions. The fit to the recorded tsunami and the deduced seismic moment, which reflects the displaced water volume, are relatively insensitive to the approach used for computing Green's functions

2018 M_W 7.9 Gulf of Alaska Earthquake: Multiple Fault Rupture in the Pacific Plate

A major (M_W 7.9) intraplate earthquake ruptured the Pacific plate seaward of the Alaska subduction zone near Kodiak Island on 23 January 2018. The aftershock seismicity is diffuse, with both NNW‐ and ENE‐trending distributions, while long‐period point source moment tensors have near‐horizontal compressional and tensional principal strain axes and significant non‐double‐couple components. Backprojections from three large‐aperture networks indicate sources of short‐period radiation not aligned with the best double‐couple fault planes. A suite of finite‐fault rupture models with one to four faults was considered, and a four‐fault model, dominated by right‐lateral slip on an SSE trending, westward‐dipping fault, is compatible with most seismic, GPS, and tsunami data. However, the precise geometry, timing, and slip distribution of the complex set of faults is not well resolved. The sequence appears to be the result of intraplate stresses influenced by slab pull, the 1964 Alaska earthquake, and collision of the Yakutat terrane in northeastern Alaska

Rupture Along 400 km of the Bering Fracture Zone in the Komandorsky Islands Earthquake (M_W 7.8) of 17 July 2017

The 17 July 2017 Komandorsky Islands M_W 7.8 earthquake involved arc-parallel right-lateral patchy strike-slip faulting along ~400 km of the Bering Fracture Zone (BFZ) in the westernmost Aleutian Islands back arc. The large size of the earthquake indicates that the BFZ serves regionally as the primary plate boundary extending from the Near Islands to Kamchatka, with the fore-arc Komandorsky Sliver translating rapidly parallel to the Aleutian Trench. The slip distribution is determined by analysis of seismic, tsunami, and geodetic observations. Fault displacements of 4 to 8.5 m, mostly in the upper 15 km, but with localized extension to 20 to 30 km depth along a ~100 km long segment of the BFZ, are comparable to the possible slip deficit since the last major earthquakes in this region in 1849 and 1858, given an estimated 5.1 cm/yr rate between the Komandorsky Sliver and the Bering Plate

Assessing r2SCAN meta-GGA functional for structural parameters, cohesive energy, mechanical modulus and thermophysical properties of 3d, 4d and 5d transition metals

The recent development of the accurate and efficient semilocal density functionals on the third rung of Jacob's ladder of density functional theory such as the revised regularized strongly constrained and appropriately normed (r2SCAN) density functional could enable the rapid and highly reliable prediction of the elasticity and temperature dependence of thermophysical parameters of refractory elements and their intermetallic compounds using quasi-harmonic approximation (QHA). Here, we present a comparative evaluation of the equilibrium cell volumes, cohesive energy, mechanical moduli, and thermophysical properties (Debye temperature and thermal expansion coefficient) for 22 transition metals using semilocal density functionals, including local density approximation (LDA), the Perdew-Burke-Ernzerhof (PBE) and PBEsol generalized gradient approximations (GGA), and the r2SCAN meta-GGA. PBEsol and r2SCAN deliver the same level of accuracies for structural, mechanical and thermophysical properties. Otherwise, PBE and r2SCAN perform better than LDA and PBEsol for calculating cohesive energies of transition metals. Among the tested density functionals, r2SCAN provides an overall well-balanced performance for reliably computing the cell volumes, cohesive energies, mechanical properties, and thermophysical properties of various 3d, 4d, and 5d transition metals using QHA. Therefore, we recommend that r2SCAN could be employed as a workhorse method to evaluate the thermophysical properties of transition metal compounds and alloys in the high throughput workflows