American Petroleum Institute

Selecting Rotary Drilling Equipment, Procedure for
 N BULL D10

Annotation

FOREWORD

a. This bulletin (First Edition, Dec. 1966) was prepared by a Subcommittee on Rating Capacity of Rotary Drilling Rigs, J. E. Hellinghausen, The Atlantic Refining Company, chairman, which functioned under the jurisdiction of the American Petroleum Institute's Steering Committee on Drilling and Production Practice. This edition supersedes the First Edition, was prepared by an ad hoc task group chaired by J. E. Hellinghausen, Atlantic Richfield Co., and was approved by the API Executive Committee on Drilling and Production Practice. Its purpose is to describe a system of analysis which will help to select a suitable rig for drilling a specific well, avoiding use of a rig that is either too large or too small.

b. This procedure presumes that depth ratings alone are not definitive, because wells in different areas require emphasis on different rig functions. For example, in drilling hard rock with frequent bit changes, hoisting capacity is of primary importance and hydraulic capacity needed to clean the bottom of the hole and circulate out cuttings is of lesser importance because of the low rate of penetration. In drilling soft formations the penetration rate is often limited by the effectiveness of bottom-hole scavenging, and the hydraulic energy available at the bit becomes very important. Since fewer bit changes are needed to drill soft formations, hoisting capacity is of lesser importance. Drill-string torque and rotary-table horsepower are also much greater with increased rates of penetration into soft formations.

c. Procedures outlined in the bulletin are divided into two categories, aims of which are:

1. To provide a plan of analysis which will be useful in determining the performance capabilities of the several rig functions which are required for the drilling of a specific well (Sections 1 and 2 ).