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.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/1542 |
| Date | 17 February 2005 |
| Creators | Long, Maximilian Mark |
| Contributors | Juvkam-Wold, Hans |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | 1588696 bytes, electronic, application/pdf, born digital |
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