SHORT COURSE: ROCK TYPING AND FLOW UNIT

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On Saturday, March 7th 2014 UI SC AAPG conducted a short course entitled “Rock Typing and Flow Unit” Presented by Al-Hafeez from Petrochina International and Ananto Wibisono from Pertamina Hulu Energy as Guest speaker. The course started at 1.00 p.m. and attended by 45 students from University of Indonesia and the neighborhood Universities. Al-Hafeez described about basic of rock typing and Ananto Wibisono described the application of rock typing and flow unit and dynamic model.

Basic rock typing described the definition of rock type and petrophysical parameters such as porosity, permeability, and capillary pressure which would help geoscientists to determine rock type. Rock type is certain rocks which are classified according to petrophysical parameter such as porosity, permeability, etc. (Schlumberger). The other definition of rock type is a tight cluster of PC curves for a narrow range of pore throat radius and porosity and permeability for rocks that have similar geological characteristics.

Rock type determined by porosity, permeability, and capillary pressure. There are two definitions of porosity. Porosity in terms of engineering are divided to effective porosity and total porosity while porosity in terms of geology divided to primary porosity and secondary porosity. Porosity mainly influenced by grain packing, grain shape (e.g. sphere or cube), and grain size distribution. There were several methods in measuring porosity:
1. Direct method (laboratory test and core)
2. Use of formation density log
3. Use of formation sonic log

Permeability is the rock’s ability to transmit fluid, measured in milidarcies. There are four controls on permeability such as Grain size, Bedding (Linear beds in series & parallel), Pore geometry, and Stress condition.

Rock type and facies are related to each other. Facies is a body of rock with specified characteristics. The relationship between rock type and facies is where one rock type can be found in several facies.

Static modelling had same definition with reservoir modelling which is a method to describe the condition of a reservoir, with time were not included or stopped at the time where not influenced by borehole. Well location trajectory, core data, regional structure data, seismic data and log data are needed for modelling. Facies modelling is also needed to spread the rock type, with steps:
Variogram Facies → Facies Distribution → Facies Generated from Seismic Inversion

Flow unit is rock which has many common petrophysical properties in the model field. There were steps in flow unit workflow:

1. Windland porosity – permeability plot
2. Constructing a Stratigraphic Modified Lorenz Plot (SMLP) foot by foot
3. Interpreting a Stratigraphic Modifies Lorenz Plot (SMLP) foot by foot
After brief presentation from the two speakers, there were discussion session with the audience. Several questions are asked. The course ended at 4 and the last activity is a photo sesio

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