Determining the true weight-on-bit for diamond bits

Conference · Sat Oct 01 04:00:00 EDT 1983 · Soc. Pet. Eng. AIME, Pap.; (United States)

OSTI ID:5293604

Winters, W J; Warren, T M

Diamond bit hydraulic lift can be a major force that reduces the true weight-on-bit as much as 15,000 lb. This can cause significant errors in the measured weight. A pump-off test must be conducted to determine the true weight on a diamond bit. Diamond bit pump-off force is governed by the total pressure drop and the shape of the radial pressure profile beneath the bit. The terms effective pump-off area and apparent nozzle area are used to characterize a bit's pump-off effect. The values for these terms can be determined from pump-off test data. Equations are given for doing this. This paper explains how to run pump-off tests in the field. Two methods, referred to as a drill-off test and a slack-off test, are presented. Both methods provide reliable measurements of a diamond bit's pressure drop and the resultant hydraulic lift. Field examples show that significant increases in hydraulic lift can be an indicator of bit wear. Pump-off force can double in cases of minor bit dulling. Six-fold increases have occured in cases of severe gauge wear. Slack-off tests work particularly well with positive displacement mud motors. Test data can be interpreted to determine the relative rate of bit wear and indicate problems with the mud motor bearings.

• Research Organization: Amoco Production Co.
• OSTI ID: 5293604
• Report Number(s): CONF-8310121-
• Conference Information: Journal Name: Soc. Pet. Eng. AIME, Pap.; (United States) Journal Volume: SPE11950
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020300* -- Petroleum-- Drilling & Production
03 NATURAL GAS
030300 -- Natural Gas-- Drilling
Production
& Processing
CARBON
DATA
DIAMONDS
DRILL BITS
DRILLING
DRILLING EQUIPMENT
ELEMENTAL MINERALS
ELEMENTS
EQUIPMENT
EXPERIMENTAL DATA
FIELD TESTS
FLUID MECHANICS
HYDRAULICS
INFORMATION
MEASURING METHODS
MECHANICS
MINERALS
NONMETALS
NUMERICAL DATA
PRESSURE DROP
TESTING
WEAR
WEIGHT MEASUREMENT
WELL DRILLING