An integrated analytical approach is presented that predicts water breakthrough timing of producing wells in the absence of surveillance (sparse PLTs, reservoir pressure and PTA) and seismic data. It is critical to understand water movement because 20% of the wells in the reservoir have produced water and are now closed for production due to lack of water handling facilities. Results are compared to existing dynamic models which are unable to accurately predict water breakthrough timing.

This approach uses production and tubing head pressure data along with gamma ray logs and wells’ saturation data to provide insights into reservoir properties. It combines geological study along with classical analytical methods like Stiles’ calculations and Rate Transient Analysis (RTA) to understand and predict the movement of water in the reservoir. The approach uses RTA for estimating key reservoir properties and Stiles’ method to calculate water breakthrough timing in the wells. After combining inferences from all data, sweep efficiency calculations are used to corroborate the water breakthrough timingspredicted by dynamic model with analytically calculated timings. Detailed algorithms and workflows are provided.

Findings from geological study of this oilfield in the Middle East and results from Rate Transient Analysis show that water is moving preferentially in certain areas in the reservoir. Combining this concept of preferential water movement with Stiles and sweep efficiency calculations predicts water breakthrough of wells that have broken water within a range of 3 months when compared to history. Converting the conceptual model into a geocircular grid for simulation enables the model to test different geological scenarios and capture uncertainties. The new history-matched models not only predict water breakthrough timing of the wells but also cover a range of geological uncertainties. Better forecast of water production helps calibrate the upcoming water handling facility at the site for improved production from the field.

The novelty of this approach is in the simplicity and speed with which it can solve a complex problem. It overcomes a very common hurdle of data uncertainty and unavailability to answer the pertinent question of water breakthrough timing at each producer well using standard analytical techniques.

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