A New Practical Approach to Rotary Drilling Hydraulics

Abstract

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. Abstract This paper presents a simple, practical and accurate method of selecting jet bit nozzle sizes. Rather than calculating friction losses in the drilling system, a measure of total friction loss is taken from the standpipe and a graphical solution of pressure loss across the bit is subtracted from the standpipe reading, resulting in the actual measurement of system pressure losses. Drilling hydraulics are based pressure losses. Drilling hydraulics are based on maximum bit horsepower, hydraulic impact, or jet velocity and are all dependent on a predetermined friction loss in the system. predetermined friction loss in the system. This method may be used to maximize any one of the three. Because mud properties and hole conditions change, nozzle size selection is made from data obtained prior to pulling a dull bit out of the hole. A work graph is presented, and typical field data are used in working example problems. Introduction The subject of rotary drilling hydraulics has received a great deal of attention in the literature. Excellent papers have been written by Bobo, Kendall and Goins, and Kelly. Recent trends have been to maximize bit hydraulic impact. Examples will be worked in this paper which will maximize hydraulic impact and bit horsepower. The derivation of the maximum horsepower, impact force, and jet velocity equations are presented in an excellent paper by Kendall and presented in an excellent paper by Kendall and Goins. Conditions that are necessary for maximizing any of these three parameters are listed without derivations in Table 1. Graphs are presented for obtaining circulation rates for various pump liners, stroke length, and strokes Graphs 1A and 1B). A nomograph of annular velocities-vs-circulation rates for various hole and drillpipe size combinations is presented (Graph 2). The method for constructing the work graph from which nozzle sizes are selected is presented. Field examples are solved in the discussion. Discussion The coordinate system upon which the work graph is constructed is log-log. The left-hand section of the work graph is used to calculate the bit pressure loss. The right-hand section of the work graph provides a scale for plotting system pressure loss as a function of circulation rate.

A Multiple Regression Approach to Optimal Drilling and Abnormal Pressure Detection

“…The expected bit life is given by (19) where m is the slope of a plot of parasitic pressure drop vs flow rate on log-log paper. Note that by operating in accordance with Eq.…”

“…Theoretical considerations indicate a value of 1.8 for m. However, Scott has recently reported measuring m values as low as 1.0. 19 An evaluation of the proposed optimization scheme has indicated that in many cases a considerable (The drillability parameter, which is based on Eq. 1, is somewhat analogous to the lCd-exponent" developed by Jorden and Shirley 11 using a more simplified penetration rate equation.)…”

“…19 The standpipe pressure is measured at both a normal circulating rate and a reduced circulating rate. The pressure drop through the bit is then estimated at both circulating rates using the orifice equation or a Hydraulic Slide Rule.…”