Journal of Geotechnology and Energy
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ISSN 2720-3581
Issue Date
2021
Volume
Vol. 38
Number
No. 4
Description
Journal Volume
Journal of Geotechnology and Energy
Vol. 38 (2021)
Projects
Pages
Articles
Displacement efficiency in tight sandstone based on fractional flow curve using relative permeability data
(AGH University of Science and Technology Press, 2021) Khlaifat, Abdelaziz Lafi
In tight gas sandstone, relative permeability is an essential special core analysis dynamic test that can be used to estimate injectivity, secondary recovery, production rate, reservoir simulation, residual gas saturation, and effective water management. Having about 65% of hydraulic fracturing fluid not to flow back and stay in the reservoir results in having the tight sandstone gas reservoir to involve multi-phase flow, namely water and gas. During the hydraulic fracturing job both imbibition and forcibly imbibition processes take place while during fracturing fluid cleanup and gas production drainage flow becomes dominant. The steady state flooding process was used to measure the relative permeability curves for a tight sandstone core sample collected from Travis Peak Formation at a depth of 8707 ft. The measurement process involved the performance of a series of steady state experiments with different gas-water injection ratios. The fractional flow curve has been plotted, based on the measured relative permeability, and used to calculate the displacement efficiency for flow through such tight porous media. The measurement showed relatively high irreducible water saturation (31%) and low residual gas saturation (6%). The measured gas relative permeability decreased slowly at a constant rate with increased wetting fluid saturation. The obtained fractional flow curve does not follow the s-shape behavior observed in a conventional reservoir. The results obtained showed that displacement efficiency can be enhanced by increasing water viscosity. Water viscosity can be increased by adding some polymer materials, however this is beyond the scope of this paper.
The improvement of mud displacement from the annular space of the borehole in terms of the selection of washing fluids and pre-flushes
(AGH University of Science and Technology Press, 2021) Formela, Małgorzata Maria
One of the most important steps in drilling a well is cementing the annular space between the casing and the rock formation. This process is significant because of the stabilization of the well and effectively separation of the consecutive rock horizons. It is essential that cementing ensures the durable and effective insulation of the rock mass. The complete displacement of the drilling fluid from the annular space is particularly important due to a number of negative phenomena related to its insufficient extrusion. The cement slurry pressed through the annular space displaces the mud but is unable to thoroughly remove the residue left behind sufficiently. The subject of the laboratory research was to check how selected washer affect the efficiency of displacing drilling fluid from the annular space of the borehole. In addition, the tests included the determination of the optimal washing time and optimal pumping rate of the washing fluid.