Casing Burst Design Criteria for Kick Pressure Control
Authors: Kastor R.L. 
Published: December 2007

This paper was prepared for the 47th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in San, Antonio, Tex., Oct. 8–11, 1972 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 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. 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.

The paper presents a burst design criterion for surface and protective casing strings based upon the pressure profile that occurs during circulating out a gas bubble following a well kick. The rationale for the design criterion is presented and the design procedure explained. presented and the design procedure explained

Introduction

The internal pressures to which protective or surface strings will be subjected are going to result from a "kick" that may occur during the drilling operation. There is a limit to the pressure that a protective or a surface string pressure that a protective or a surface string can retain before the added pressure on top of the hydraulic column inside the pipe will produce a pressure at the shoe sufficient to produce a pressure at the shoe sufficient to fracture the formation and cause a loss of whole mud. The surface pressure, which when applied to the top of a liquid and gas column inside the casing will break down the formation at the casing shoe, is the highest surface pressure that can be contained by the formation and, therefore, is the highest surface pressure for which the casing string need be designed.

WELL KICK PRESSURE PROFILE

A well kick or rise in pit level is a result of an inflow of a foreign fluid into the wellbore as shown in Fig. 1, due to encountering a bottom-hole pressure, Pbh, higher than the mud hydrostatic pressure, Pf, Once a bubble of foreign fluid is in the wellbore, it can only be removed by circulating it to the surface and out of the well. The profile of maximum pressure as this bubble moves up the wellbore is the pressure the hole or casing must contain. The pressure profile at various stages is shown in Figs. 2A, profile at various stages is shown in Figs. 2A, 2B and 2C. The composite of these profiles as shown in Fig. 2D describes the type pressure relation on which the design may be based.

OBSERVED MAXIMUM SURFACE PRESSURES

Observations of maximum kick pressures over a period of years has established that the maximum pressure, Pa(max), which occurs as the bubble readies the surface may be taken as one-third the bottom-hole hydrostatic pressure anticipated for the next casing string. That is,

..........................................(1)

where PS = design surface pressured i = mud weight of next string H = depth to next string