fax 01-972-952-9435. AbstractAn integrated transient wellbore/reservoir model is described and applied to investigate the liquid loading in a gas well. The well produces from a storage reservoir with water coning from its aquifer.The integrated model shows that the water cone causes the gas flow rate from each gas layer to decrease and the liquid holdup in the wellbore to increase. Depending on reservoir conditions, the well may enter into a mode of unsteady production during which the gas flow rate cycles over a period of several days. The reason for this unsteady flow is uncovered by the simulation.Simulation results are compared with operational experience and full field reservoir simulations. The integrated model provides more realistic results compared to methods where the reservoir and the wellbore are modeled separately.

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In EOR-operations, the single-well chemical tracer test (SWCTT) has been proven as a secure and stable methodology for measuring oil saturation prior to and after application of EOR-measures. SWCTTs can be used to measure residual oil saturation in a near-well region up to about 10 m from the wellbore, and has been used in several hundred studies, in particular in the US. Current simulation of SWCTT requires a reactive transport modelling tool that allows for a hydrolysis reaction involving four chemical compounds, in addition to other chemical tracers used in specific tests. Today compositional reservoir simulators are usually applied to simulate SWCTTs. In this paper we show that the SWCTT modelling can be made much simpler, without compromising a correct description of the reactive transport process. The formulation of the solution exploits the fundamental assumption that tracers do not affect the phase transport. A fast post-processing tracer simulation technique is introduced to solve single well tracer transport in real-life reservoir cases. The partitioning and reactions of the tracer components is solved fully coupled with the tracer transport, and partitioning between phases is described by a convenient formulation and the ester hydrolysis reaction is modelled in an efficient manner. The post-processing is based on previously solved reservoir simulation runs and gives significant savings in CPU-time. Using an experimental case and one field case, we demonstrate the practical improvement achieved by the new method, and investigate effects of numerical smearing. Our main conclusion is that the formulation is important to enhance correct evaluation of SWCTT results.

fax 01-972-952-9435. AbstractAn integrated transient wellbore/reservoir model is described and applied to investigate the liquid loading in a gas well. The well produces from a storage reservoir with water coning from its aquifer.The integrated model shows that the water cone causes the gas flow rate from each gas layer to decrease and the liquid holdup in the wellbore to increase. Depending on reservoir conditions, the well may enter into a mode of unsteady production during which the gas flow rate cycles over a period of several days. The reason for this unsteady flow is uncovered by the simulation.Simulation results are compared with operational experience and full field reservoir simulations. The integrated model provides more realistic results compared to methods where the reservoir and the wellbore are modeled separately.