Designing Lost Circulation Pills for Polymer
Based Drill-in Fluids
Specially
designed non-damaging lost circulation pills (LCP) are being
effectively applied for drilling depleted zones worldwide. Optimizing
the LCP compositions stop the lost circulation effectively and protect the
production zone from liquid and solids invasion significantly. Shape, particle
size distribution and concentration of the lost
circulation materials (LCM) are key parameters determining the effectiveness of
LCP.
In this study,
the Permeability Plugging Apparatus (PPA) is utilized
to evaluate effectiveness of various LCMs in curing the lost circulation.
Micronized cellulose fibers and sized calcium carbonates are
used as LCM in different concentrations and in different particle size
distribution. Lost circulation zones are simulated
using the ceramic disks and slotted disks. Ceramic disks with nominal pore sizes 5 and 10
microns (around 500 mD and 2D) are characterized in
terms of pore size distribution using the computerized image analysis
technique. Filter cake quality, spurt loss, filtrate volume
and return permeability are basic parameters to be evaluated in this
study. Tests are performed at 150 F
and 500 to 1500 psi of differential..
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