Air and Gas Drilling Manual

Applications for Oil, Gas, Geothermal Fluid Recovery Wells, Specialized Construction Boreholes, and the History and Advent of the Directional DTH

William C. Lyons,James H. Stanley,Francisco J. Sinisterra,Tom Weller

• Publisher: Gulf Professional Publishing
• Year: 2020
• ISBN:
  9780128157930
• Edition: 4
• Topic: Technology & Engineering
• Subtopic: Chemical & Biochemical Engineering
• Index: Technology & Engineering

Air and Gas Drilling Manual, Fourth Edition: Applications for Oil, Gas and Geothermal Fluid Recovery Wells, and Specialized Construction Boreholes, and the History and Advent of the Directional DTH delivers the fundamentals and current methods needed for engineers and managers engaged in drilling operations. Packed with updates, this reference discusses the engineering modelling and planning aspects of underbalanced drilling, the impacts of technological advances in high angle and horizontal drilling, and the importance of new production from shale. in addition, an in-depth discussion is included on well control model planning considerations for completions, along with detailed calculation examples using Mathcad.

This book will update the petroleum and drilling engineer with a much-needed reference to stay on top of drilling methods and new applications in today's operations.

• Provides key drilling concepts and applications, including unconventional activity and directional well by gas drilling
• Updated with new information and data on managed pressure drilling, foam drilling, and aerated fluid drilling
• Includes practical appendices with Mathcad equation solutions

Chapter 1: Introduction, Calculation Programming, and Unit Systems

Abstract

This initial chapter clarifies the differences between the American version of the British Imperial System (BIS), which is known as the United States Customary System (USCS), and the other widely used System International d’Unites (SI). It defines the USCS as a gravitational system with basic specific units in length, force, and time. The SI is defined as an absolute system having basic specific units of length, mass, and time. The usage of each Worldwide system is discussed and how they relate to each other. Both unit systems are utilized through most of the new 4th Edition of the Air and Gas Drilling Manual.

Keywords

Calculation programming; Performance drilling; Underbalanced drilling; Unit systems; Physical mechanics; Basic units; Usage; Unit conversions

1.1: Introduction

There is a wide variety of air and gas drilling operations being used by many diverse industries in a great variation of locations around the world. These vary from the air- or gas-assisted drilling of very shallow subsurface boreholes for large and small construction projects to the drilling of extremely deep vertical to horizontal boreholes used for the extraction of important natural resources (e.g., fresh water resources, geothermal fluids with dissolved minerals in live steam, natural gas, and crude oils). Both industry and government entities sponsor these operations. From the inception of the rock and soil drilling technologies for perceived needs in industries, the individual inventors within these markets have been dedicated to innovations that would make these drilling operations safer, reliable, and cost-effective. Such innovations are followed by active development of nearly all new ideas and ultimately the commercial application within the various industries.

Deep hole drilling air and gas technologies used for discovery and recovery of crude oil, natural gas, and geothermal fluids have in the past been limited to use in mature sedimentary basins. Mature sedimentary basins are older basins that have competent subsurface rock formations, are well cemented with natural minerals, and have been tectonically uplifted such that little formation water remains in near-surface porous and fractured beds. Usually, their geological ages are prior to about 65 million years. Modern air and gas drilling technology and operations began in the United States in the 1930s. It is presently being used in many drilling operations throughout the world’s many oil and gas producing geologic provinces. It is important at this time in the development of this technology that the basic principles of the technology be communicated in a manner that all drilling personnel will understand.

Innovation in subsurface drilling equipment has been usually initiated by smaller business entities or individual inventors. These innovators are the “tinkers” in the industry and the ideas for changes often come from the field hands who operate and handle these tools on a day-to-day basis. There are many examples of these innovations coming from these innovative small business entities over the past seven decades. Examples of such important early innovation are as follows: the top drive rotary system, the downhole compass sub, the bent sub, for direction drilling, the formation coring bit, the downhole positive displacement motor (PDM), the downhole air hammer, and the reverse circulation drill string. Therefore, this manual will discuss not only the existing important technologies but also some of the new innovations that are entering the various industry markets. It is believed that this kind of exposure to the new innovations taking place in industry will hasten the acceptance and application of these inventions into the larger industrial markets. In essence, the larger markets will become “infected” earlier from the successes in the smaller markets.

Larger diameter shallow and intermediate depth wells are often drilled with reverse circulation techniques. These techniques and their associated equipment are easier to manufacture to incorporate any new innovations and test them. Thus, virtually unknown ideas, like reverse circulation drilling, may someday be used in deep well drilling with small diameter drill string BHAs. That will likely necessitate the invention of new materials and fabrication techniques that have not yet been invented to create the concept of flexible dual wall pipes.

Air and gas drilling technologies account for approximately 10% of the world’s land oil and gas drilling operations. It was a somewhat higher percentage a decade or so ago, but over that decade, the oil and gas drilling industry was in a recession and drilling operations are always the first budget item to be cut back in slow market times. With those cut backs comes a slowdown in innovations in existing technologies and their associated operations.

However, shallow drilling operations for large diameter construction holes, pipeline directional drilling of near horizontal boreholes, and cable lying (not counting auger borings) utilize close to 50% air drilling technologies with compressor pressurized air flow for removing drill bit cuttings.

This manual shows the engineer or engineering technician how to use the included equations in each chapter to create calculation programs that can be used to predict the air (or gas) pressures at specific positions inside the drill string and in the annulus around the drill string in the flow loop. This will give an accurate estimate of the injection pressure required from the selected compressor package. For a direct circulation operation, the loop calculation sequence must be initiated with the only known pressure in the loop. That is the exit pressure at the exit end of the blooey line with the entrained drill bit cuttings (and any injected or formation liquids) being lifted from the bottom of the borehole. If the operation is using a “solid-gas buster” or a device to separate the solids or dust from the return flow from the bottom of the borehole, then the known pressure will be at the exit of the gas from the solid-gas separator. For a reverse circulation operation using a dual-walled drill string, the initiating pressure will be at the exit from the blooey line that is connected to the top of the inside pipe flow space of the dual wall drill pipe. The calculation will proceed in reverse, down flow space of the inside pipe, through the drill bit nozzles and up the annulus space in the dual wall drill pipe to the compressor injection pressure. Here again, if a solid-gas separator is being used, the initiation pressure at the separator exit will be used, which is also atmospheric.

1.2: Calculation Programming

Engineers and drilling supervisory personnel need to make predictive calculations in order to make their drilling operations efficient and cost-effective. The prediction calculations for air and gas drilling technology are complicated and will require the creation of calculation computer programs. There are sophisticated air and gas programs available commercially. But in the tradition of most engineering fields, once the basic outline of the program has been outlined, we tend to hand the “care and feeding” of the program over to the computer science department. The authors have chosen to use MathCad as our primary tool to communicate to the readers the details of how air and gas drilling predictive calculations are made. These MathCad solutions are very transparent and are written in a sequence that an engineer or engineering technician would do if they were to do the calculation by hand. In the event, the consultancy or company requires the use of engineering programming languages like FORTRAN, MATLAB, Pascal, Basic, Visual Basic, Java, C, and C ++. The reader can easily copy our sequence into the other programming languages.

The detailed MathCad sol...