Optimum Well Spacing for the Gas Reservoirs Of the Mexican-Republic
Authors: Chacon H. Francisco 
Published: December 2007

This paper was prepared for the 48th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Las Vegas, Nev., Sept. 30-Oct. 3, 1973. 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 request 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 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
A correlation of the economic studies made in PEMEX during the last 20 years for determining the optimum well spacing for the gas reservoirs of Mexico is presented. Four main variables were involved in the calculations: the original gas at reservoir conditions, the gas classification, the optimum number of wells and the time of exploitation. The results are presented as graphs, nomographs and in a slide rule for applications in the recently discovered gas reservoirs.

Introduction
In the oil business, optimum well-spacing determination has always been a topic of economical interest and of engineering analysis. Because of this, several works have been prepared on the subject by the world oil prepared on the subject by the world oil industry.
For the gas reservoirs of Mexico, computer programs have been developed to optimize the programs have been developed to optimize the economical appraisals made of the well spacing. These optimizations were performed in terms of the maximum present value of future earnings. In many instances, the results only gave a late idea of the well spacing that would have convenient to use, for at the time they were obtained the reservoirs had been almost entirely developed. Under these circumstances, it was not always possible to fit the grid of the drilled wells to that of the optimum well spacing, especially in the case of multiple reservoirs. However, in such instances the results were always useful because they allowed the determination of the number of wells required to exploit one of the gas reservoirs, allowing the remaining wells to produce from the rest of the gas or oil reservoirs.
Due to the great availability of the calculations described, a correlation of most of them was made with the CDC 6400 computer fitting programs. For that purpose, several correlation programs. For that purpose, several correlation parameters were tried. Among those used parameters were tried. Among those used were the original volume of the gas measured at the pressure and temperature conditions of the reservoir, the simple classification of the gas of the reservoir into wet or dry, the geographical location of the gas reservoirs of Mexico and the programmed exploitation schedules. This resulted in the most significant parameters to correlate with the optimum number of wells, arranged in seven-spot patterns, to exploit a particular gas reservoir. particular gas reservoir. Besides the above mentioned parameters, many others have to influence the correlations with the optimum number of wells but, perhaps, to a lesser extent. The correlations obtained, however, can only be considered as preliminary approaches to the gas well spacing.