Schlumberger

Reservoir Evaluation

Unlocking heavy oil reservoirs

Clarifying the oil type, quantity, and volume, and estimating potential flow rates are the basic components for unlocking heavy oil reservoirs. Because reservoirs are often stacked within a field and different fluid types or varying compositions may be present a variety of production methods, including thermal enhanced oil recovery (EOR), may be required to produce each basin.

During reservoir evaluation studies developers must keep the long-term strategy in mind, selecting the path that leads to the fastest release of cash flow so that, as needed, facilities may be built to enable sequential production from other reservoirs. A pilot project is an essential part of this process.

Reservoir extent

Reservoir studies delineate the basin’s lateral extent and thickness—from all scales and angles. Seismic services often help define the reservoir’s reach, and when combined with LWD and MWD data and wireline logs, they provide the input to build reliable reservoir models.

Hydrocarbon volume

To calculate basic economic viability, an estimation of the volume of hydrocarbons in the reservoir is required. By combining various measurement types and using specially calibrated tools, we can define the difference between oil and water contacts in heavier reservoirs.

Porosity and saturation

Oil volume is determined using accurate porosity and saturation readings by integrating a variety of data acquisition methods and tools specially designed to work in challenging reservoirs.

Nuclear magnetic resonance tools

Nuclear magnetic resonance (NMR) tools are used to evaluate the reservoir and provide saturation, permeability, and fluid profiling for hydrocarbon volume and viscosity evaluation and producibility. 

Geological modeling

Heavy oil reservoirs are often associated with soft, unconsolidated near-surface basins where wellbore stability can be an issue during drilling or production, and poorly-sorted heterogeneous sands can hinder steam chamber growth. In cold heavy oil production with sand (CHOPS), accurate sedimentary classification is also needed to build models.

Simulation for producibility

Sand channels (or wormholes), the result of sand production in a geologic basin, mean that special reservoir simulation techniques must be incorporated to adequately model CHOPS and other production mechanisms. These must accurately describe the flow paths, pressure drawdowns, and stimulated productivity that occur because of those channels.

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