Practical Procedure To Predict Cresting Behavior of Horizontal Wells

Abstract

Water and gas cresting in horizontal wells are important phenomena in reservoirs that have an aquifer or a gas cap. In practical situations, many reservoirs are produced under supercritical rates, and a breakthrough of the displacing phase becomes inevitable. At the beginning of a reservoir simulation study, it is desirable to make an estimate of the breakthrough time and the post-breakthrough behavior. Grid sensitivity runs are also required to obtain the appropriate gridblock sizes. An accurate representation of cresting behavior requires a very fine grid, which is not always practical. In this work, a procedure was developed to obtain accurate breakthrough times by use of just coarse grid simulations. The flow equations were written in dimensionless form, and important parameters affecting multiphase flow were identified. Simple correlations for a quick estimate of breakthrough time, maximum oil rate, and post-breakthrough behavior were derived on the basis of an appropriate set of dimensionless variables and an extensive number of simulation runs. The effects of gridblock size and grid pattern were investigated in detail. Effects of rate, mobility ratio, well drainage area, well height, and endpoints and shapes of relative permeability curves were also included. A procedure to derive pseudofunctions, either by numerical correlations or coarse grid simulations, is also presented. These pseudofunctions can be used to improve the performance of coarse grid simulations. An optimum grid pattern to start a reservoir simulation study is proposed.An application with real data shows that the correlations and procedures derived are reliable and accurate and can be used for quick estimates before starting a reservoir simulation study.

Water Breakthrough Shape Description of Horizontal Wells in Bottom-Water Reservoir

“…In the 1990s, with wide application of Hele-Shaw model, 2-D (two-dimensional) physical experiment had been gradually used to investigate performance of horizontal wells in reservoirs with bottom water. Permadi's research showed that water cresting will first present at heel of horizontal segment; then it would gradually move toward to toe [1]; Souza established a new mathematical model to analyse water breakthrough time and flow regime after breakthrough with reservoir parameters, compared with that of numerical simulation by Eclipse, Jiang, Tove Aulie, Francols M, Giger and Wang et al investigated the water cresting of horizontal well with the mathematical model above and got the similar conclusion [2][3][4][5][6].…”

“…When [10,8,5,2,1], namely, decreasing flow velocity, the dimensionless breakthrough time was 1445Δ , and water cresting shape was as shown in Figure 9.…”

Field Validation of a Non-logging Alternative Method for the Prediction of the Location of Water-Cresting in Horizontal Wells for Water-Drive Reservoirs

“…In 1995, Aulie et al proposed a steady-state analytical model for the prediction of oil and water production at the supercritical rate and found good agreement with the experimental results carried out with a visual cell at low pressure . In 1998, de Souza et al reported a correlation model to predict the breakthrough time, maximum oil rate, and the postbreakthrough behavior of gas and water-cresting in both the horizontal and vertical wells as a function of the grid block size, grid patterns, rate, mobility ratio, drainage area, well height, end point, and shape of the relative permeability . In 2000, Umnuayponwiwat and Ozkan conducted a modeling study on the effect of wellbore pressure drop on the breakthrough time of water and gas coning in horizontal wells and found that wellbore hydraulic has a strong effect on the shape and timing of the breakthrough .…”

Method of Predicting the Location of Water Cresting for Horizontal Wells in a Water-Drive Reservoir for Early Prevention

“…31,32 De Souza et al reported a numerical correlation of the effect of grid block size, grid patterns, rate, mobility ratio, drainage area, well height, and endpoint and shape of relative permeability on breakthrough time, maximum oil rate, and postbreakthrough behavior for water and gas cresting in horizontal and vertical wells. 33 Bahadoori followed with a simple-to-use correlation for dimensionless breakthrough time of water/gas coning and optimum horizontal well placement for horizontal wells in homogeneous and anisotropic reservoirs as a function of the dimensionless rate and density difference ratio. 34 Umnuayponwiwat and Ozkan conducted modeling work on the effect of wellbore pressure drop on the breakthrough time of water and gas coning into a horizontal well and reported that wellbore hydraulics have a strong effect on the shape and breakthrough of the coning.…”