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Title Revised productivity index equation to improve transient history match for the Capacitance Resistance Model
Publication Date
Date Accessioned
Degree MSin Engineering
Discipline/Department Petroleum engineering
Degree Level masters
University/Publisher University of Texas – Austin
Abstract The Capacitance Resistance Model (CRM) is a data-driven reservoir model developed for well surveillance and management. The model is gaining popularity in reservoir engineering community because of its simplicity and ability to provide insights on well-to-well connectivity during water/gas flooding project. Furthermore, the model can be used to optimize injection scheme or even plan for infill drilling. The model was built on the assumptions that during waterflooding the dominant flow regime is semi-steady state. However, to extend the functionality of this model to unconventional reservoirs, a productivity index model that works well in transient flow regime should be investigated. In this thesis, two different productivity models are proposed. The first is the combined productivity index model. This model originates from the analytical solution of single compartment model and the constant behavior of the productivity index in fracture-dominated flow. These two components are then linearly combined to form a new productivity index model. The second is the logistic productivity index model, which uses a well-studied logistic growth model to capture the S-shaped production profile starting from a transient linear flow regime to a late-time fracture-dominated regime. These two proposed productivity index models are incorporated into the fundamental CRM equation, respectively, to derive the logistic CRM and combined CRM. To validate the models, multiple reservoir simulations were conducted to generate synthetic cases capturing both transient linear flow and fracture-dominated regime, and then the proposed models were fitted to the simulation data using Microsoft Excel Solver. Case validation is also accomplished with field data. Very good history matches were obtained from these two models, and they demonstrate that with proper revision to semi-steady state model CRM is able to match production history sufficiently and quickly. In addition, the combined CRM is physics-based so it is shown that the model is able to provide insights on some important reservoir properties.
Subjects/Keywords Capacitance Resistance Model; Productivity index; Unconventional; Flow regime; Linear transient; Pseudo-steady state
Contributors Lake, Larry W. (advisor)
Language en
Country of Publication us
Record ID handle:2152/46243
Repository texas
Date Retrieved
Date Indexed 2020-10-15
Grantor The University of Texas at Austin
Note [department] Petroleum and Geosystems Engineering;

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…production over time. The model can fit the oil rate and cumulative production data from Bakken Shale really well. 3 Chapter 2: Simulation Validation of Single Compartment Model The application of the CRM model is currently limited to pseudo-steady state

…flow regime. The reason is that the productivity index equation integrated into the material balance formulation only applies to pseudo-steady state. To extend the applicability of CRM, a productivity index equation for long period of transient regime…

…33 Figure 23: Combined productivity indices calculated with various steady state productivity indices ...........................................................................35 Figure 24: Combined productivity indices calculated with various beta…

…45 xii Figure 30: Production history with various steady state productivity indices .......47 Figure 31: Production history with various beta values.........................................47 Figure 32: Production history for well 74 in the middle…

…linear transient flow and semi-steady state respectively. The smaller the formation permeability, the longer the linear transient regime. The cell (300, 1, 1) represents the pressure boundary between two neighboring fractures. Under homogeneous…

…transient linear (Wattenbarger and El-Banbi1998) and semi-steady state regime (Walsh and Lake, 2003). The purpose of this thesis is to investigate the ways to improve the history match of CRM during linear transient flow regime…

…fractures. When the pressure propagation reached the middle point, a transition is observed from linear decline on a log-log scale to a linear decline on a semi-log scale. This indicates the inception of the semi-steady state flow, a flow condition dominated…

…by the impermeable flow boundary (Walsh and Lake, 2003). In comparison, the simulation with maximum time step of 1 day shows only the linear transient flow regime and semi-steady state regime, since the resolution is not enough to capture…