American Petroleum Institute

OIL-WELL CEMENTING PRACTICES IN THE UNITED STATES
 N OIL WELL CEMENT

Annotation

FOREWORD: Each year in the United States several thousand wells are drilled and completed - some productive of oil or gas and some dry - and during this drilling and completion most of these wells are cased, with the casing set in the bore hole surrounded by oil-well cement. This book has been written about the process of placing this cement and it covers how this and related operations are carried out.

The compositions used in cementing are basically portland cements or cements prepared by supplementing portland with additives or by variations in grinding or other manufacturing processes. Compositions other than portland cement are sometimes used in wells and often applied using methods closely similar to those used with portland cement. However, this book should in no way be interpreted to mean that portland-cementing methods can invariably be used with other compositions.

Indeed, no part of this book should be interpreted as an American Petroleum Institute recommendation for any procedure, method, practice, or equipment.

Some parts of the process of "cementing a well" are closely similar wherever they might be carried on; while other parts may vary widely, dependent upon geographical location. Nomenclature or terminology particularly vary from one area to the next.

One example of this variation is the expression for cement-slurry density which, like drilling-fluid density, has commonly been expressed both as pounds per gallon and pounds per cubic foot. In this one instance an API recommended unit has been devised, this being pounds per square inch per 1,000 ft of depth (psi/M ft); and this unit is used as the principal one throughout this volume with the others shown as alternative expressions.

Another of the wide variations in terminology is found in descriptions of casing strings. For example a "conductor string" is typically .a light-wall casing used only to shallow depths to prevent caving of loose earth, to bring drilling-fluid returns up through the water at marine locations, or to augment corrosion protection. It may be anything from 20 ft to a few hundred feet in depth and in the latter case is nearly identical to "surface casing".