An Investigation Into the Need of a Dynamic Coupled Well-Reservoir Simulator

Abstract

Within the research framework of the "Integrated System Approach Petroleum Production" (ISAPP) knowledge center of TNO, TU Delft and Shell, the necessity of taking the interaction between dynamic reservoir and dynamic well behavior into account when optimizing a producing asset is investigated. To simulate dynamic phenomena in the well and in the reservoir, a dynamic multiphase well simulation tool (OLGA) and a dynamic multiphase reservoir simulator (MoReS) have been used. Both simulators have been coupled using an explicit scheme. The dynamic well simulator, the dynamic reservoir simulator and the coupled dynamic well-reservoir simulator have been used to simulate a realistic test case which consists of a horizontal well with three inflow sections located in a thin oil rim. A number of scenarios are investigated that play a crucial role during different stages of the well's lifetime: naturally occurring phenomena, e.g. coning, and production dynamics, e.g. shut-in. The results of dynamic well simulations, dynamic reservoir simulations and coupled well-reservoir simulations are presented and an overview is given of the cases where the results of the coupled simulations are significantly more accurate in comparison to stand-alone well or reservoir simulations. For gas coning it is shown that the coupled simulator has much faster pressure transients after gas breakthrough than the dynamic reservoir simulator. Therefore, the coupled well-reservoir simulator should be used to simulate gas breakthrough and to optimize production using gas coning control. For small time scale phenomena, order of less then one day, the well and reservoir transients overlap. Simulations show that the coupled simulator is essential for an accurate prediction of the well-reservoir interaction during these small time scale phenomena. Introduction Production instabilities are undesirable and play a crucial role in the production lifetime and ultimate recovery of any reservoir. These instabilities can arise from or be governed by the interaction between the well and the reservoir.1 Production instabilities can be subdivided into two groups. Firstly, the naturally occurring dynamical phenomena, such as coning and slugging. Secondly, the production dynamical phenomena, such as shut-in, clean-up and gas lift heading. Figure 1 displays the time and spatial scales for different naturally occurring and production dynamical phenomena. The values of the time and spatial scales are indicative and based on experience. There are several phenomena which have a certain amount of overlap. In these areas it is expected that the well dynamics are strongly influenced by the reservoir dynamics and visa versa. Simulations are widely used to predict oil and gas production. The current status of these simulations is to either use a dynamic well model combined with some analytical reservoir model2 or to use a dynamic reservoir model combined with either lift tables or a steady state well model.3, 4 The disadvantage of these models is the fact that they underestimate the pre-mentioned well-reservoir interactions and therefore give non-realistic production forecast in cases where well-reservoir interactions play a crucial role.

Dynamically Coupled Reservoir and Wellbore Simulation Research in Two-Phase Flow Systems: A Critical Review

“…Table 3 summarizes the most relevant aspects of various coupling examples. M, N, B, SF, V F Winterfeld [30] M, N, B, SM, V F Holmes et al [12] M, ?, B, DF, M F Stone et al [25] M, T, C, DF, M I Coats et al [9] M, N, C, ?, M F Bhat et al [16] S, T, B, ?, H I Nennie et al [1] M, T, B, SF, M E Sagen et al [23] M, T, B, ?, M F Pourafshary [22] M, T, C, DF, V F Leemhuis et al [19] M, T, B, SF, M E Livescu et al [20] M, T, C, DF, M F Livescu et al [50] M, T, B, DF, M F Semenova et al [85] M, T, C, DF, M F Twerda et al [29] M, T, B, SF, M F Bahonar et al [15] S, T, B, ?, V F Shirdel [52] S, N, C, ?, H F Pan and Oldenburg [21] M, T, C, DF, V F Gao [129] M, N, B, SM, V&H I Forouzanfar et al [48] M, T, C, DF, V F Cao et al [17] M, N, C, ?, M F Olivares [99] M, N, C, SM, V F Redick [130] M, N, B, ?, V I Tang et al [96] M, N, C, DF, H F Galvao et al [33] S, T, C, ?, V E Galvao et al [133] S, T, C, ?, V E Basirat et al [32] M, T, C, DF, V F Battistelli et al [31] M, T, C, DF, V F Raad et al [34] M, T, B, ?, V E Liao et al [35] M, T, B, ?, H F Legend: Coupled reservoir/wellbore simulation: M = multiphase; S = singlephase; T = thermal; N = non-thermal; B = black oil; C = compositional; SF-separated flow; SM-semi empirical model; DF-Drift-Flux; V-vertical well; H-horizontal well; M-multilateral well; ? -unknown.…”

“…The dynamic interaction between wellbore and reservoir research is essential to solve transient flow problems, such as wellbore storage, gas lift, coning, near-well cleanup, liquid loading, slugging, shut-in, start-up, smart wells, and reservoir management and forecast [1,2]. In multi-phase (gas, water, and oil) flow, the pore saturation and temperature and pressure propagation changes in a reservoir respond to propagation ranging timescales from hours to decades.…”

“…Millier [13] might be the earliest scholar who studied transient interactions between wellbore and reservoir for well testing in geothermal wells. Other coupled reservoir/wellbore simulators were established to simulate dynamic flow problems between reservoirs and wellbores [1,3,. Numerical wellbore simulation contains a mass equation, momentum equation, and energy equation [36,37].…”

Modeling fully transient two-phase flow in the near-wellbore region during liquid loading in gas wells

“…They used steady-state relationships to characterize both the reservoir and the wellbore. Nennie et al (2007) simulated the flow from a horizontal well with three inflow sections located in a thin oil rim, each individually regulated by an inflow control valve (ICVs). They used a commercial transient wellbore simulator to mimic the well's response, and a full-field numerical reservoir simulator to model the reservoir, including the near wellbore.…”

Modeling and Analysis of Temperature Transients Caused by Step-Like Change of Downhole Flow Control Device Flow Area

“…Vicente showed in his isothermal model that the traditional approach of decoupling wellbore flow from reservoir flow in horizontal wells do not capture the interaction between them at early times (Vicente, Sarica et al 2001). Alberts analyzed the dynamic behaviour in the well and reservoir identifying the time and space scales at which the well-reservoir coupling becomes important (Alberts, Belfroid et al 2007). Alberts analyzed the dynamic behaviour in the well and reservoir identifying the time and space scales at which the well-reservoir coupling becomes important (Alberts, Belfroid et al 2007).…”