Postdoctoral Research Associate
I am a computational geoscientist and petroleum engineer. I am interested in coupled multi-physics processes of flow, transport, and mechanical deformation in porous media. Applications are in the areas of enhanced oil recovery, groundwater remediation, induced seismicity, and microfluidics. I emphasize a mathematical and computational approach in simulating the physical system, identifying the dominant coupling mechanisms, and expressing the mechanisms in terms of reduced-order models.
I received my masters in Petroleum Engineering from the Dept. of Energy Resources Engineering at the Stanford University and my PhD from the Dept. of Civil and Environmental Engineering at MIT. I have worked in the oil and gas industry as a reservoir engineer. My experience is in waterfloods, CO2 floods, tight gas, and solution-gas drive reservoirs in US and India.
 C. Nicolaides, B. Jha, L. Cueto-Felgueroso, and R. Juanes. Impact of viscous fingering and permeability heterogeneity on fluid mixing in porous media. Submitted.
 B. Jha and R. Juanes. Coupled multiphase flow and poromechanics: a computational model of pore-pressure effects on fault slip and earthquake triggering. Water Resources Research, 50, doi:10.1002/2013WR015175 (2014).
 B. Jha, L. Cueto-Felgueroso and R. Juanes. Synergetic fluid mixing from viscous fingering and alternating injection. Physical Review Letters, 111, 144501 (2013).
 B. Jha, L. Cueto-Felgueroso and R. Juanes. Quantifying mixing in viscously unstable porous media flows. Physical Review E, 84, 066312 (2011).
 B. Jha, L. Cueto-Felgueroso and R. Juanes. Fluid mixing from viscous fingering. Physical Review Letters, 106, 194502 (2011).
 B. Jha and R. Juanes. A locally conservative finite element framework for the simulation of coupled flow and reservoir geomechanics. Acta Geotechnica, 2:139-153 (2007).
1. Best Doctoral Thesis Award, Civil and Environmental Engineering, MIT, 2014
2. Outstanding Student Paper Award, Hydrology, American Geophysical Union Fall Meeting, 2010
3. Outstanding Student Paper Award, Hydrology, American Geophysical Union Fall Meeting, 2009
4. Schoettler Fellowship, Civil and Environmental Engineering, MIT, 2009
5. Gold Medal, Petroleum Engineering, Indian School of Mines, 2001
Fluid mixing in porous media
Mixing of fluids is an important and complex phenomenon. It controls many natural and industrial processes. Fluid mixing in porous media and in low Reynolds number flows is especially difficult because of the absence of turbulence. Development and control of mixing in such flows is a challenge and an active area of research.
Mixing from viscous fingering
In enhanced oil recovery techniques such as miscible flooding where CO2 is injected to mix with and displace crude oil, recovery efficiency can be increased by developing miscibility between the two fluids. We show that viscous fingering, a type of hydrodynamic instability, can be used to induce disorder in the flow and thereby enhance mixing. Tip-splitting and channeling during viscous fingering are two different mechanisms of mixing. Shown below is a snapshot of the mixture concentration field during flow of a less viscous fluid (light color) displacing a more viscous fluid (dark color).
We develop a two-equation model for the concentration variance and mean scalar dissipation rate to quantify the evolution of degree of mixing in a viscously unstable displacement. Fastest mixing is achieved by optimizing the interplay between tip-splitting and channeling mechanisms during viscous fingering. Shown below is a snapshot of the concentration field during flow of the less viscous fluid, initially distributed as blobs, through a more viscous ambient fluid in a periodic box.
Stokes flow in a Hele-Shaw cell serves as a simple analog for porous media flow. We study spreading and mixing of slugs of different viscosities flowing between two parallel glass plates. Shown below are the concentration fields of slugs of three miscible fluids--red, blue, and green. Ratio of viscosities: blue/red = 55, green/blue = 5. More mobile red fluid flows through the less mobile blue fluid.
Mixing at low Reynolds number can be enhanced by alternating injection of slugs of different viscosities. We show that the synergetic action of alternating injection and viscous fingering leads to a dramatic increase in mixing efficiency. Top: mild viscosity contrast, Middle: strong viscosity contrast, Bottom: optimum viscosity contrast.
Mixing and dilution in heterogeneous formations
Heterogeneity of the porous medium is another source of disorder in the flow that causes spreading and dilution of groundwater contaminants. Shown below are the concentrations of a contaminant in a vertical section through an aquifer with groundwater flow. Initially, the contaminant started as a thin slug (light color) instantaneously placed in the background flow of water (dark color). The flow direction is from left to right. Fluid properties of the contaminant and water are identical. Top: mildly heterogeneous medium, Bottom: strongly heterogeneous medium.
Concentration field during transport of two passive tracers (blue and red colors) with the groundwater (green) flow. Initially, the two tracers were distributed as blobs near the left side of the domain. The flow direction is from left to right.
Coupled flow and deformation
The coupling between subsurface flow and geomechanical deformation is critical in the assessment of the environmental impacts of groundwater use, underground liquid waste disposal, geologic carbon dioxide storage, and exploitation of shale gas reserves. In particular, seismicity induced by fluid injection and withdrawal is a matter of public concern. We develop a new computational approach to model coupled multiphase flow and geomechanics of faulted reservoirs.
Coupled simulation of multiphase flow and geomechanics
Vertical displacement for uncoupled (left) and coupled (right) simulations in a 12km x 6km x 4km aquifer with two oblique faults. Slip prescribed on the faults through rupture events at every 200 yr interval and creep events. Boundary conditions: zero x and y displacements at x+ and x- faces, bottom boundary fixed. For the coupled case, wells are at constant pressure. Initial condition: lithostatic stress, hydrostatic pressure. Grid is distorted with displacements magnified by a factor of 80.
Triggering of earthquakes
Cross-section (x-z) view of vertical displacement field in a faulted geologic basin. Aquifer is overpressurized due to carbon dioxide injection, which leads to rupture on a normal fault and subsequent earthquake. Shown below is the vertical displacement after the fault slip.