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Well control is of the utmost importance during drilling operations . Numerous well
control incidents occur on land and offshore rigs . The consequences of a loss in well
control can be devastating . Hydrocarbon reservoirs and facilities may be damaged ,
costing millions of dollars . Substantial damage to the environment may also result . The
greatest risk , however , is the threat to human life .
As technology advances , wells are drilled to greater distances with more complex
geometries . This includes multilateral and extended -reach horizontal wells . In wells with
inclinations greater than horizontal or horizontal wells with washouts , buoyancy forces
may trap kick gas in the wellbore . The trapped gas creates a greater degree of uncertainty
regarding well control procedures , which if not handled correctly can result in a greater
kick influx or loss of well control .
For this study , a three -phase multiphase flow simulator was used to evaluate the
interaction between a gas kick and circulating fluid . An extensive simulation study
covering a wide range of variables led to the development of a best -practice kick
circulation procedure for multilateral and extended -reach horizontal wells .
The simulation runs showed that for inclinations greater than horizontal , removing the
gas influx from the wellbore became increasingly difficult and impractical for some
geometries . The higher the inclination , the more pronounced this effect . The study also
showed the effect of annular area on influx removal . As annular area increased , higher
circulation rates are needed to obtain the needed annular velocity for efficient kick
removal . For water as a circulating fluid , an annular velocity of 3 .4 ft /sec is
recommended . Fluids with higher effective viscosities provided more efficient kick
displacement . For a given geometry , a viscous fluid could remove a gas influx at a lower
rate than water . Increased fluid density slightly increases kick removal , but higher
effective viscosity was the overriding parameter . Bubble , slug , and stratified flow are all
present in the kick -removal process . Bubble and slug flow proved to be the most efficient
at displacing the kick . |
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