ANALYSIS OF OIL/WATER EMULSION IN THE PRODUCTION AND DUMPING ZONES OF OIL WELL BY CFD TECHNIQUE

Oil/water mixture production in oil production wells is a common phenomenon. It
is of high interest to the oil industry to process the oil/water separation in the downhole,
by hydrocyclone technology. Oil and water separation methods have focused on the
separation process and the hydro fluid behavior within the separator body while there
is a lack of studies and simulations on the wellbore flow behavior before and after the
separation. Accordingly, this work is directed to investigate the mixture flow structure
in the production and in the water dumping zones. A computational modelling and
numerical simulation using CFD technique is described in this thesis for the oil and
water flow inside the wellbore before and after separation by counter current
hydrocyclone. The simulation was conducted for a two-phase flow using ANSYS-Fluent
15 software and it was attempted to visualize the volume fraction and density profiles
in a natural downhole environment. The well geometries and the oil/water production
candidates at the downhole have been adopted from a real well in an offshore field in
Malaysia. Four cases of oil-to-water mixing ratios have been considered, as 90:10,
70:30, 50:50 and 30:70, and the separator efficiency was assumed to be 90%. The
results illustrate the great complexity of oil in water flows, reflecting the many
competing processes, like turbulence, gravitational separation, droplet interaction and
the shear between the two liquids and with the solid surfaces, which are occurring in
the annulus. In the zone before the separator, the production zone, distribution of the
oil volume fraction depends highly on the mean oil volume fraction and the vertical
length of the zone without perforations. The contour results from the simulation showed
that the phases mix and achieve uniform distribution as the flow proceeds down the
channel. The present simulation could be used to better predict the behavior of oil/water
mixture flow inside the wellbores with the presence of a hydrocyclone, and also can be
modified to simulate the wells with production at lower zone and dumping at upper
zone.