How tandem power motors improve drilling performance

Journal Article · Sat Oct 01 00:00:00 EDT 1994 · World Oil; (United States)

OSTI ID:6933832

Califf, B; Johnson, M ^[1]

---

1. Drilex Systems, Inc., Houston, TX (United States)

Tandem power section positive displacement mud-motors (TPS-PDMs) can increase penetration rate when used with tricone and PDC bits. This is achieved by increasing the available output torque and shaft rotational speed by reducing pressure drop per stage in the power section. Early PDMs were single-lobe 1:2 rotor-stator ratio motors. Horsepower produced by these PDMs was a result of high output-shaft rotational speeds and low output torque. Most later PDMs have rotor-stator ratios ranging from 3:4 to 10:11. This change to a higher ratio increased output torque, but also caused a decrease in rotational output-shaft speed. Motor power, a product of torque and speed, has not changed significantly in any particular motor size since the early PDMs. Modern day PDC and tricone ''motor'' bit use requires that PDMs provide high torque and medium to high (180- to 300-rpm) output shaft speeds. This paper discusses the four primary variables in the basic design of any PDM power section for a given diameter tool. Variables are: rotor-stator lobe ratio; lobe spiral pitch; maximum design pressure drop; and number of stages.

• OSTI ID: 6933832
• Journal Information: World Oil; (United States), Vol. 215:10; ISSN 0043-8790
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
03 NATURAL GAS
42 ENGINEERING
DRILLS
DESIGN
PERFORMANCE
TORQUE
NATURAL GAS WELLS
WELL DRILLING
OIL WELLS
DRILLING
DRILLING EQUIPMENT
EQUIPMENT
WELLS
020300* - Petroleum- Drilling & Production
030300 - Natural Gas- Drilling
Production
& Processing
422000 - Engineering- Mining & Underground Engineering- (1980-)