Perforation Collapse: Failure of Perforated Friable Sandstones

Abstract

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. This paper was prepared for the SPE-European Spring Meeting 1976 of the Society of Petroleum Engineers of AIME, held in Amsterdam, The Netherlands, April 8–9, 1976. 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 publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor 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 To simulate perforation collapse, a number of thick-walled cylinders of rock material have been loaded to failure. To cover a wide range of possible loading situations, a series of possible loading situations, a series of experiments has been performed with various ratios of axial and radial loads. In addition the influence of perforation diameter on failure has been investigated. The experiments were carried out with two types of friable sandstone, selected on the basis of Brinell hardness. The thick-walled cylinder experiments were numerically analysed with the aid of elastic-plastic theory. For this purpose the stress-strain behaviour of the formation material was determined by performing numerous triaxial experiments on massive core samples. From the calculated stress and strain distributions at the experimentally observed failure load an instability criterion could be derived in terms of limiting value of shear strain. Introduction In our investigations on sand influx in producing wells we studied the stability of producing wells we studied the stability of perforation tunnels. A description of perforation perforation tunnels. A description of perforation stability is of practical significance, because it is indispensable in deciding whether a given well will remain sand-free during its productive life. In cases where perforation failure is foreseen, predictions cover the following practical aspects: predictions cover the following practical aspects:*prediction of the moment of failure allowing a timely decision on a sand exclusion technique to be applied, in order to avoid costly remedial treatment*indication of the zone(s) prone to perforation failure, which will Provide guidance in matters of completion policy, particularly when this knowledge is available before a particular well is perforated. Instabilities are attributed to erosion of grains and/or chips from the perforation wall on the one hand and to failure of the surrounding rock on the other. In a separate paper the effect of erosion due to gas flow on the stability of perforation tunnels has been reported. In the perforation tunnels has been reported. In the present contribution a laboratory investigation present contribution a laboratory investigation on the mechanical failure of perforated formation material, i.e. friable sandstone from the Rotliegendes formation of the Groningen gas field, is described.