Changes

There is no universally applicable set of rules by which to define flow units. Dividing a reservoir into flow units requires an integration of stratigraphic, sedimentological, structural, petrographic, petrophysical, and field performance data. The process is summarized as follows ([[:file:flow-units-for-reservoir-characterization_fig1.png|Figure 1]]):

There is no universally applicable set of rules by which to define flow units. Dividing a reservoir into flow units requires an integration of stratigraphic, sedimentological, structural, petrographic, petrophysical, and field performance data. The process is summarized as follows ([[:file:flow-units-for-reservoir-characterization_fig1.png|Figure 1]]):

* Identify the major lithofacies, vertical sequences, and depositional environments from available core. Relate lithofacies, at the whole-core scale, to their mineralogical, textural, and pore level properties and to permeability, [[porosity]], fluid saturations, and capillarity as measured on core plugs. Establish consistent relationships between rock properties and petrophysical properties.

* Identify the major lithofacies, vertical sequences, and depositional environments from available core. Relate lithofacies, at the whole-core scale, to their mineralogical, textural, and pore level properties and to permeability, [[porosity]], fluid saturations, and capillarity as measured on core plugs. Establish consistent relationships between rock properties and petrophysical properties.

* Establish the three-dimensional distribution of flow units by correlation of calibrated wireline logs. Knowledge of environments of deposition of the reservoir sequence is important to interpreting the style of correlation to be used and the expected patterns of external and internal geometry of any flow unit (see [[Lithofacies and environmental analysis of clastic depositional systems]]). During correlation, the flow unit zonation established in individual cored wells may change somewhat. Tying correlation horizons around a loop is critical because individual correlation sections alone can be deceptive.

* Establish the three-dimensional distribution of flow units by correlation of calibrated wireline logs. Knowledge of environments of deposition of the reservoir sequence is important to interpreting the style of correlation to be used and the expected patterns of external and internal geometry of any flow unit (see [[Lithofacies and environmental analysis of clastic depositional systems]]). During correlation, the flow unit zonation established in individual cored wells may change somewhat. Tying correlation horizons around a loop is critical because individual correlation sections alone can be deceptive.

* Test the validity of flow units established by consideration of production logs (see [[Production engineering methods]]), flow tests of small intervals, oil and water geochemistry (see [[Laboratory methods]]), repeat formation tester (RFT) surveys (see [[Wireline methods]]), injectivity logs, tracer surveys, and any available data on patterns of production through time. Modify the flow unit definitions as needed to accommodate the physical measurements of flow, if a rationale can be found for the differences.

* Test the validity of flow units established by consideration of production logs (see [[Production engineering methods]]), flow tests of small intervals, oil and water geochemistry (see [[Laboratory methods]]), repeat formation tester (RFT) surveys (see [[Wireline methods]]), injectivity logs, tracer surveys, and any available data on patterns of production through time. Modify the flow unit definitions as needed to accommodate the physical measurements of flow, if a rationale can be found for the differences.

The distribution of petrophysical properties such as porosity and permeability can be mapped within flow units using well control only or by applying geostatistical procedures to create stochastic realizations of these distributions “conditioned” on the well data (see [[Geological methods]]). Geostatistical techniques that have a strong stochastic component are consistent with, and complementary to, the flow unit concept, which is itself mostly deterministic.

The distribution of petrophysical properties such as porosity and permeability can be mapped within flow units using well control only or by applying geostatistical procedures to create stochastic realizations of these distributions “conditioned” on the well data (see [[Geological methods]]). Geostatistical techniques that have a strong stochastic component are consistent with, and complementary to, the flow unit concept, which is itself mostly deterministic.