An Analytical Method for Relationship Between Hydraulic Diffusivity and Soil Sorptivity

A simple method was developed to relate soil sorptivity to hydraulic diffusivity and water absorption experiments were conducted utilizing one-dimensional horizontal soil columns to validate the relationship. In addition, an estimation method for hydraulic diffusivity with disc infiltrometer was developed. The results indicated a favorable fit of the theoretical relation to the experimental data. Also, the experiment with disc infiltrometer for estimating the diffusivity showed that the new method was feasible.

Rheology of a Viscous-Plastic Liquid in a Porous Medium

The hydrodynamics of the capillary flow of a viscous-plastic liquid in cylindrical rectilinear pores is considered, as a result of which the structural velocity distribution over the pore cross section is obtained. Analytical solutions are proposed for the equations of hydraulic diffusion and nonlinear filtration for a non-Newtonian fluid in a cylindrical porous medium. It is noted that when a non-Newtonian fluid flows in a porous medium, the filtration equations take a nonlinear form due to the effective viscosity, shear, and yield stresses taken into account in its structure. The proposed solutions make it possible to evaluate the state of the porous medium and its main parameters (permeability, hydraulic diffusion, and effective viscosity coefficients). The obtained solutions are compared with existing experimental data for non-Newtonian oils.

Identification of Aquifer Properties in the Eastern Part of Kushtia District, Bangladesh

The present study has been undertaken to depict spatial distribution of different aquifer parameters in the eastern part of Kushtia district through a detailed hydrogeological survey. For this investigation, 119 lithologs and 92 pumping test data have been used. These data have been processed, analyzed, interpreted and krigged for the spatial assessment of the aquifer properties viz. transmissivity, hydraulic conductivity, hydraulic diffusivity, specific yield, radius of influence, and specific drawdown. It is seen from the investigation that the transmissivity and hydraulic conductivity values obtained from the pumping tests of the wells are varying from 1811 m2/day to 2568 m2/day and 32.5 m/day and 61.5 m/day respectively, the hydraulic diffusivity being ranging from 181,143 m2/day to 256,788 m2/day. The estimated specific yield of 17.97% - 23.46% supports that the area is dominated with coarse grained sands. This study reveals that the distribution of deep tube wells in the area are not within the radius of influence (638 - 760 m) each other, but few shallow and hand tube wells existed within the radius of influence. The estimated specific draw down is varying from 57 m/cumec to 126.1 m/cumec. From the overall analysis, it is found that the area is favorable for groundwater exploration.

Fast production and water-breakthrough analysis methods demonstrated using Volve Field data

When producing from conventional fields,the well rates are primarily constrained by the production-system in the early years of the field-life,while later in the field-life the production rates are primar-ily constrained by the reservoir deliverability.For the post-plateau production period,the reservoir deliverability will no longer potentially exceed the production-system well-rate constraints.Tradition-ally,analytical equations are used in a nodal analysis method that balances the pressure at the well inflow point from the reservoir(inflow performance relationship;IPR)with the pressure required for the vertical lift performance(VLP;or vertical flow performance;VFP)from the same point upward.A faster and simpler approach is proposed in the present study.Whereas,the classical IPR solutions are based on a constant well-rate solution of the diffusivity equation,use of a constant bottomhole pressure assumption can bypass the need for nodal analysis type pressure matching solutions to obtain the well rate.Instead,the well rate can be directly computed from the pressure decline in the reservoir and any production system capacity constraint can be imposed on the theoretical well rate due to the reservoir quality.The merits of the new approach are explained and illustrated by way of a detailed production analysis case study using open-access data from the Volve Field(Norwegian Continental Shelf).In addition,the case study of the Volve Field wells demonstrates a new water-breakthrough analysis method.

Stable expression and control parameters in the numerical simulation of unsaturated flow

The Richards’equation describes the flow phenomenon in unsaturated porous media and is essential to hydrology and environmental science.This study evaluated the numerical stability of two different forms of the Richards’equation.Sensitivity analyses were performed to investigate the control parameters of the equation.The results show that the h-form Richards’equation has better applicability for calculating variable saturation flows than theθ-form Richards’equation.For the h-form Richards’equation,the hydraulic conductivity of the soil in the low-suction range and the specific moisture capacity in the high-suction range primarily influenced the solution.In addition,sensitivity analyses indicated that the saturated hydraulic conductivity,initial condition,and air-entry pressure have a higher sensitivity to the simulation results than the saturated water content,rainfall intensity,and decline rate of hydraulic conductivity.Moreover,their correctness needs to be guaranteed first in numerical simulations.The research findings can provide a helpful reference for improving the reliability of numerical simulations of unsaturated flows.