To avoid problems with under gauge hole and BHA changes it is important to ensure the following to reduce the riskof stuck pipe: bits and stabilisers shall always be gauged after each trip if the bit pulled is undergauge, the whole of the section drilled by that bit is reamed unless torque records clearly show … Changing a Bottom Hole Assembly

When dealing with areas of formation instability it is necessary to: – trip cautiously through swelling formations – pick up and ream midway through each stand (if hole conditions are severe, more frequent reaming may be required) – trip through tight sections using slow rotation and circulation (after pulling into a tight spot, run back … Formation Instability

The following are possible indicators of hole cleaning problems: excessive overpull on connections and trips reduced overpull when pumping excessive fill after trips erratic and increasing torque while drilling lack of cuttings over shakers (or large slugs of cuttings followed by periods of very few cuttings). Solutions to Hole Cleaning Problems Circulation, no matter how … Hole Cleaning

The Drilling Programme shall indicate any permeable formations which may lead to differential sticking, particularly if the risk of differential sticking is considered to be high. Data Acquisition An estimate of the problem formation pressure shall be made using the best offset data available. If good, and recent, RFT, or producing well information is available, … Preventing Differential Sticking

In normal overbalanced drilling conditions, a pressure differential exists between the mud column and the formation pressure. In situations where the formation pressure is significantly lower than that exerted by the mud column, the drillstring may be forced against the wellbore wall and, if the pressure difference is large enough and acts over a significantly … Differential Sticking (Cause of Stuck Pipe)

Mechanical sticking occurs as a result of one or more of the following 8 conditions: 1. inadequate hole cleaning 2. formation instability 3. key seating (not often a problem but has happened occasionally) 4. running into underagaugehole 5. accumulation of cuttings 6. drilling plastic formations 7. large boulders falling into the hole 8. running tools … Mechanical Sticking (cause of stuck pipe)

If the pipe becomes stuck, and pulling and working the string has failed to free the pipe, spotting fluids should be used around the stuck part of the string, in an attempt to eliminate the root cause of the sticking. Differential Sticking Such fluids are designed to attack and break down the filter cake thus … Spotting Fluids to Free Stuck Pipe