Mr. Erik Milito - The House Committee on Natural Resources ...

ISOLATING POTENTIAL FLOW ZONES DURING WELL CONSTRUCTION 71
C.3.5 Preventing Losses
C.3.5.1 Drilling Fluid Properties
Drilling fluid properties can be optimized to prevent losses using the following:
— proper solids control management,
— keeping the fluid density as low as possible,
— maintaining gel strengths and yield point at the lowest levels that will effectively clean the hole and effectively
suspend barite and cuttings,
— preventing excessive filter cake build-up by controlling fluid loss,
— using hydraulic prediction software to predict ECD and determine optimum fluid properties.
C.3.5.2 Minimize Surge Pressures
Surge pressures can be minimized by:
— staging in the hole to prevent excessive circulating pressures;
— rotating the pipe to mechanically shear the drilling fluid reducing gel strength before turning on the pumps, and
bringing the pumps up slowly;
— monitoring and controlling pipe running speeds;
— using available hydraulics modeling software for predicting surge pressures;
— calculating annular flow and running casing slowly enough to avoid high pressure (speed of lowering each joint,
not the average speed).
C.3.5.3 Downhole Equipment
<strong>The</strong> following downhole equipment practices will help reduce ECD to limit losses:
— using downhole pressure measurements to monitor and manage ECDs in real time;
— using BHA components with maximum annular flow paths across the tools;
— installing auto-fill and various enhanced flow by-pass equipment to minimize surges while running casing, note
well control implications while running casing;
— using downhole tools that allow for high concentrations of LCM.
C.3.6 Identifying the Loss Zone
Quickly identifying where the loss zone is located will greatly enhance the performance of the treatment used to
counter the lost circulation. Temperature logs, spinner surveys, noise logs, LWD data analysis and stress modeling,
connection flow monitoring analysis, lost circulation computer model simulations, and offset well drilling fluid loss data
are a few of the techniques used to identify where the suspected loss zone may be located. If a NAF is used, the
suspected loss zone could be identified during a short trip by very high resistivity readings in an otherwise nonproductive
zone.