Shallow gas kicks

Conference · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6773957

Nokleberg, L; Schuller, R B; Sontvedt, T

Drilling through shallow gas pockets in the North Sea and in other areas represent a risk for loss of control with subsequent uncontrolled gas blowouts. The diverter system is intended to convey this gas to lee side of the platform. Statistics show that the diverter system fail in about 50% of the cases they are used to handle shallow gas kicks. The flow conditions in diverter systems currently employed in the North Sea are so severe that it cannot be expected that the diverter system can withstand a shallow gas kick in more than a few minutes. The erosion rate can be as high as 1-2 mm/min, and this is an alarming figure. Veritec has investigated various forms of severe damages to a diverter system which failed under a gas blowout in the North Sea. The damages were caused by erosion of sand particles at high velocity and malfunction of valves. Calculations indicated high gas velocity (near sonic) in the diverter during the blowout. Velocity in the diverter system can be reduced by increasing diameter of the diverter lines and throttling (a choke) at outlet. By this combination erosion rates may be reduced with a factor of several thousand. The downhole pressure will not be affected by this improved diverter design.

• OSTI ID: 6773957
• Report Number(s): CONF-870993-
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
030200* -- Natural Gas-- Reserves
Geology
& Exploration
42 ENGINEERING
423000 -- Engineering-- Marine Engineering-- (1980-)
ACCIDENTS
ATLANTIC OCEAN
BLOWOUTS
CONTROL EQUIPMENT
DESIGN
DIVERTORS
DRILLING
EQUIPMENT
FLOW REGULATORS
FLUIDS
GASES
NATURAL GAS WELLS
NORTH SEA
OFFSHORE DRILLING
OFFSHORE PLATFORMS
SAFETY
SEAS
SURFACE WATERS
VALVES
VELOCITY
WELLS