Fast Water-Coning Evaluation Method

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, to be held in New Orleans, La., 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 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 Many approximate methods have been published for making fast evaluations of published for making fast evaluations of reservoir behavior when water coning is involved. Based on theoretical or experimental research, these methods usually provide a fairly close approximation of the critical flow rate and the breakthrough time under restricted geometric and drive conditions. However, when economic necessities make production above the critical flow rate production above the critical flow rate inevitable, the WOR increase versus time or oil production must be evaluated. Heretofore this evaluation has required the use of complicated and costly mathematical models. This paper proposes a new method combining experimental correlations using dimensionless numbers with a simplified analytical approach based on the assumption that the front shape behaves like a current line, in an equivalent model of different shape. This method can be numerically processed quickly and easily. It gives a sufficient approximation of both the critical flow rate and the breakthrough time as well as of the WOR increase, the pressure drop, the productivity index and the minimum flow value below which it would be necessary to decrease the flow rate for excluding water production. The process can be applied to any thick homogeneous reservoir which is horizontally fed. Conversely, the method can be used for approximately determining the optimum completion and withdrawal rate. The results obtained using this method have been compared with those from numerous diphasic flow experiments using different-sized physical models. The initial conditions and the fluid characteristics were varied to a large degree during these experiments. Although the calculations do not take into account the capillary forces existing in the model, there is satisfactory agreement between the different results: agreement which is expected to be sufficient for making a fast prediction and especially for choosing the prediction and especially for choosing the penetration depth. penetration depth. An example is given of how this method is applied to a topical problem. This is followed by a discussion of the influence on water-coning behavior of the different parameters that usually characterize displacement.