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American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. This paper was prepared for the 46th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, held in New Orleans, Oct. 3–6, 1971. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal, provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Introduction It is sometimes desirable, when drilling for oil and gas, to drill away from the vertical so that the bottom end of the wellbore is at a given horizontal distance from the vertical. These wells are called directional wells and are drilled from offshore platforms to reduce the number of offshore structures in a particular oil or gas field. At the present, directional wells are drilled somewhat by trial-and-error, i.e., measurements of drill bit orientation are made periodically and appropriate changes are made in weight on the drill bit to increase or decrease the orientation of the bit. Stabilizers are also used near the bit to control the rate of hole deviation from the vertical. There are several articles in the literature which discuss directional drilling (and hole deviation, crooked holes, dog-legs, etc.); however, except for very few technical papers, most of the publications are general discussions of the directional drilling problem. A literature survey indicated there are very few, if any, technical publications that relate drilling variables to wellbore curvature. In 1968, the API funded a 3-year research project (API Research Project 107) at the U. of project (API Research Project 107) at the U. of Arkansas to study a directional-drilling concept proposed by the author. The directional-drilling proposed by the author. The directional-drilling concept is based on the premise that a wellbore, having constant curvature, will be drilled if the curvature of the drill collars directly above the bit is constant while drilling the hole; the deflection of the drill collars directly above the bit is a circular arc. The concept presupposes that the bit will drill in the direction it is pointing. The direction of the bit is controlled pointing. The direction of the bit is controlled by collar deflection that, in turn, depends on collar design and bit force. The research began by developing and solving a nonlinear differential equation of bending, which leads to collar design data. This phase was followed by an experimental phase, designed to verify the premise mentioned above. This paper summarizes premise mentioned above. This paper summarizes the results from the 3-year API project. The experimental work is presented first and is followed by the bending theory. LABORATORY DRILLING RIG A laboratory drilling rig (Fig. 1) was designed and built to experimentally verify the directional-drilling concept mentioned above.
- North America > United States > Arkansas (0.25)
- North America > United States > Louisiana > Orleans Parish > New Orleans (0.24)
- Asia > Middle East > Israel > Mediterranean Sea (0.24)
American Institute of Mining, Metallurgical and Petroleum Engineers Inc. This paper was prepared for the 45th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Houston, Tex., Oct 4–7, 1970. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon requested to the Editor of the appropriate journal, provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract This paper is concerned with the mathematical development and solution of a nonlinear differential equation of bending which relates to the directional drilling of oil and gas wells. The directional drilling concept in this paper is unique and is based on the premise that a directional wellbore having constant curvature will be drilled if the deflection of the bottom portion of the pipe [or drillstring] has portion of the pipe [or drillstring] has constant curvature; the constant curvature or circular arc deflection is due primarily to gravity. To achieve a circular arc pipe deflection due primarily to gravity, pipe diameter must vary along the pipe according to the solution to the differential equation of bending; pipe diameter is the dependent parameter in the pipe diameter is the dependent parameter in the differential equation. The broader purpose of the research is to develop directional drilling technology which relates the many drilling variables, such as bit weight, drilling fluid, and drill collar design, to wellbore geometry. Background It is sometimes desirable, when drilling for oil, to drill away from the vertical so that the bottom end of the well is at some appreciable horizontal distance away from the vertical. Wells of this geometry are called "directional" wells and are sometimes drilled from offshore platforms to reduce the number of offshore structures in a particular oil field. particular oil field. At the present, directional wells are drilled somewhat by the trial-and-error method, i.e., measurements of drill bit orientation are made periodically and appropriate changes are made in weight on the drill bit to increase or decrease the orientation of the bit. Stabilizers are also used near the bit to control the rate of hole deviation from the vertical. There are several articles in the literature which discuss directional drilling [and hole deviation, crooked holes, dog-legs, etc.]; however, except for very few technical papers most of the publications are general discussions of the directional drilling problem. A literature survey indicated there are very few, if any, technical publications which relate drilling variables to wellbore curvature. This report represents an attempt to develop a directional drilling technology which relates drilling variables to wellbore curvature. The directional drilling concept discussed in this report is based on the premise that a wellbore having constant curvature will be drilled if the deflection of the drill pipe directly above the bit is always circular. The circular arc deflection is developed in the section of pipe directly above the bit by using nonuniform pipe whose diameter [or cross-sectional moment of inertia] varies over its length according to the theory presented in this paper.