Cone Breakthrough Time for Horizontal Wells

Abstract

Recovery from an oil zone underlying a gas cap, overlying an aquifer, or sandwiched between gas and water can be improved by repressing the coning problem through horizontal-well drainage. Literature methods to predict coning behavior are limited to steady-state flow conditions and determination of the critical rate. The results in this paper are based on new semianalytical solutions for time development of a gas or water cone and of simultaneous gas and water cones in an anisotropic infinite reservoir with a horizontal well placed in the oil column. The solutions are derived by a moving-boundary method with gravity equilibrium assumed in the cones. For the gas-cone case, the semianalytical results are presented as a single dimensionless curve (time to breakthrough vs. rate) and as a simple analytical expression for dimensionless rates > l!J. For the simultaneous gas-and water-cone case, the results are given in two dimensionless sets of curves: one for the optimum vertical well placement and one for the corresponding time to breakthrough, both as functions of rate with the density contrast as a parameter. The validity of the results has been extensively tested by a general numerical simulation model. Sample calculations with reservoir data from the Troll field and comparison with test data from the Helder field demonstrate how the theory can be used to estimate the time to cone breakthrough and its sensitivity to the uncertainties in reservoir parameters.

Proactive control of cresting in homogeneous oil reservoirs: an experimental study

“…The effluent breakthrough times for the thick-oil and thin-oil rim reservoirs were experimentally measured, approximately 140 and 63 s, respectively. The obtained breakthrough times are in good agreement with analytical, theoretical and numerical simulations using field data, such that the closer the WOC and GOC to the well the faster the effluent(s) breakthrough time(s) at the same oil production rate (Peng and Yeh 1995;Schevchenko 2013;Papatzacos et al 1991;Omeke et al 2010).…”

Productivity and injectivity of horizontal wells. Annual report, March 10, 1995--March 9, 1996

“…This gives better results than the approaches , normally used, that is, the use of a number of blocks of the same dimension close to the well and then start doubling (or just double from the well block) [22].…”

Study of Startup Parameters Triggering Water Cresting in Wells in Bottom-Water Reservoirs

“…Critical state parameters Some researchers [13][14][15][16][17] have studied the critical state, in which the oil/water interface is stabilized at the level of the line CNC (see Fig. 2) and does not rise to the wellbore.…”