Influence of compound grease on the performance of premium connections

Journal Article · Thu Mar 01 00:00:00 EST 1990 · SPE (Society of Petroleum Engineers) Drilling Engineering; (USA)

OSTI ID:6821649

Isuru, E; Maruyama, K; Yazaki, Y ^[1]

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1. Bureau of Nippon Steel Corp. (JP)

The authors investigated the harmful effect of compound grease on premium connections. The pressure buildup of compound grease trapped between threads was measured during and after makeup of the connection. The resulting hoop stress in the coupling and the reduction in the seal interference were also measured. Mathematical models were developed to calculate coupling stress and grease pressure. Results indicate that for the conventional API buttress-thread profile, the pressure of trapped compound grease remains permanently high after the connection is made up because of the small thread-clearance area. This high pressure results in a high coupling stress and a large reduction in seal interference diameter, thereby degrading the integrity of the connection. To solve this problem, the thread profile was redesigned with a thread-clearance area larger than that of conventional buttress thread. The connection with the new thread design showed a significantly lower pressure buildup, coupling stress, and seal interference reduction than that with the conventional thread design. Therefore, premium connections with the new thread design are recommended over those with conventional buttress thread design for wells in hostile environments.

• OSTI ID: 6821649
• Journal Information: SPE (Society of Petroleum Engineers) Drilling Engineering; (USA), Vol. 5:1; ISSN 0885-9744
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
THREADED JOINTS
GREASES
CALCULATION METHODS
DRILLING EQUIPMENT
MATHEMATICAL MODELS
PERFORMANCE TESTING
RESERVOIR PRESSURE
EQUIPMENT
JOINTS
LUBRICANTS
TESTING
020200* - Petroleum- Reserves
Geology
& Exploration
990200 - Mathematics & Computers