API WORLDWIDE CEMENTING 91st Edition, January 1, 1991
Worldwide Cementing Practices
Includes all amendments and changes through Reaffirmation Notice , October 2000
Additional Comments: G04400 * W/D NO S/S
Published By:American Petroleum Institute (API)
Several thousand wells are drilled and completed annually throughout the world - some productive of oil or gas and some that are dry - yet during this drilling and completion process most of these wells are cased, with the casing set in the borehole, surrounded by cement.
In 1959, the API published the first edition of a book covering the technology of "Oil Well Cementing Practices in the United States" under the leadership of Harry N. Stansbury of the Atlantic Refining Co. Drilling and completion experts throughout the industry participated in this early project. Its contents covered cementing technology dating from the early 1920's through the mid 1950's. The major part of this cementing information, however, represented practices used after World War II until about 1956.
Since these early events in our industry, many changes have taken place in cement standardization, in cement testing, and in field practices, particularly in deep drilling. API Cement Standardization Committee 10 and its members have played a significant role in the research and development of all phases of cement technology since this original book was published. In 1987, experts within the industry and from Committee 10 were again selected to write chapters in this revised volume entitled "World Wide Cementing Practices." This revised version is an attempt to mold all the various technologies used today; no part of this book should be interpreted as an American Petroleum Institute recommendation for any procedure, method, practice or equipment.
In 1990 the processes of "cementing a well" are very similar in most parts of the world. Nomenclature and terminology may vary from one area to another; however, the basic process is about the same worldwide.
The compositions used in cementing today are essentially API cements or API cements prepared by supplementing with additives or by variations in grinding or manufacturing processes. Bonding and sealing materials other than Portland cement are rarely used in wells, yet when applied follow methods similar to those used with Portland cement.
Cementing of surface casing is one of the most uniformly followed procedures. Surface casing depth may vary from 100 to several thousand feet; its function is to protect freshwater formations, to mount wellhead equipment, and to anchor blowout-preventer equipment.
"Intermediate strings" may range from a few thousand to over 10,000 ft in depth. In some conditions they case off salt beds of moderate depth and are called "salt strings." In others they case off troublesome shales, or zones that will not withstand high fluid pressures, and for these purposes they may be called "protection strings."
"Completion strings" and/or liners represent more diversified designations. In localities where cement is used to enable such casing strings to shut off water immediately above the oil production, the term "water string" is customary.
In other areas the customary term is "oil string," and where the well may produce oil or gas or both, "completion string," "production string," "producing string," or "long string" may be used.
Where it becomes impractical to continue drilling to the depth intended for the producing string, it is sometimes set at a lesser depth as a protection string and the hole below is cased with a liner hung in the bottom of the original string.
Technology now being developed and evaluated in selected drilling areas may or may not find wide applications in the petroleum industry. Of particular interest is the drilling and cementing of horizontal wells. The use of this technology has been in fewer than 2000 of the 3.5 million wells drilled worldwide before 1990. Completion techniques in horizontal wells has been variable, yet experts will agree that the same cementing fundamentals are required as in a vertical or directional well, i.e., a well-drilled hole, proper centralization, mud conditioning to remove regions of gelled or immobile fluids before cementing, use of proper spacers and/or flushes, use of good cementing materials with emphasis on solids-settling control with no free water, and pipe movement where possible.
The chapters of this volume follow a logical sequence in relation to the development and application of cementing methods and consequently bear a fairly close relationship one to another. This relationship, however, is loose enough to permit the chapters to be read and studied individually. To facilitate such use, indexes are provided at the beginning of each chapter rather than at the back of the book.
Leadership in this major endeavor has been under API Cement Standardization Committee 10 chairman D. G. "Jerry" Calvert, Mobil Oil Company in Dallas, TX, and coordinated for Committee 10 by Dwight K. Smith, Consultant (Ret. Halliburton Services), Duncan, OK.