Carbonate Reservoir Rock Typing 15-18 Feb. 2010
The 7th Annual SPWLA Abu Dhabi Chapter Topical was the most successful of the seven conferences held to date in terms of registrant’s technical knowledge and contribution. One hundred and seventy-five plus participants traveled from Africa, Asia, North America, Middle East, South America and Europe to discuss the latest developments in reservoir rock characterization and how static properties link to dynamic flow properties for confident prediction of future reservoir performance, “Answers which Management can use to make investment decisions.”
- Geological Rock Types, Petrophysical Rock Types (often called Static Rock Types), and Dynamic Rock Types are different approaches – need clear definitions
- Objective is to populate the Geological Model with porosity, permeability and initial water saturation.
- Heterogeneity is rarely quantified through lab protocols. How representative are the values we measure? How many significant digits do you believe?
- Bigger is better with respect to sample size. The heterogeneity volume should be small compared to the sample size.
- There is a non-unique relationship between measured properties at the plug scale and geological features.
- The classical RRT scheme linking facies associations, sequence stratigraphy and diagenisis is an arduous and challenging process in carbonate reservoirs.
- Depending upon the maturity of the data, a Petrophysical Group (PG) methodology can be an immediate route to populating the geocellular space with rock types and static properties.
- The Thomeer pore geometry based approach illustrated by Saudi Aramco is very fit for purpose and links the static and dynamic properties.
- A link exists between Static Rock Types and Dynamic Rock Types (relative perm). Dynamic Rock Types need to incorporate wettability.
- Dynamic data is a key input in building / updating the static model. Validate the RRT scheme with dynamic data.
- Need to bridge the gap with numerical simulation. What does the simulation engineer need?
- Is the heterogeneity measured at the plug scale appropriative for the simulation scale?
- Permeability is directly linked to the size of the largest pore geometry.
- Entry Pressure (Pd) and permeability are directly coupled.
- Unsteady State relative permeability experiments on vuggy plugs leads to distorted curves. Recommend whole core and Steady State experiments plus direct and indirect 3D modeling.
- Sector models provide much more insight into understanding field performance than full field models.
- Saudi Aramco, ADCO, Chevron and Schlumberger showed techniques to predict rock types at the log scale.
- In agredational reservoirs the effects of diagenisis can be minimized in the permeability prediction by using a spatial clustering technique. Data regions within parasequences should facilitate more accurate perm predictions.
- High pressure mercury injection on plugs from a single facies is a key measurement for Petrophysical Rock Typing
- Saudi Aramco Petrophysical Rock Types based on Thomeer – Swanson Hyperbola’s and their parameters; BVI, G, Pd. Thomeer parameters are used to predict permeability and scale up saturation functions. Incorporating method in simulators.
- J and Brooks-Corey saturation functions may not work for carbonates. Neither truly captures the complexity of the pore geometry, nor do they upscale well.
- It was demonstrated that IFT*Cos can be predicted from fluid composition and mineralogy. This is a key to accurate saturation height work and needs to be incorporated into the dynamic model.
- Oil starts to penetrate micro pores 50 to 80 feet above free water level. Oil in microporosity of Arab D limestones is recoverable under waterflood.
- Saudi Aramco investigating relationship between Thomeer Rock Types and relative permeability curves.
- Adjust saturation functions to account for Paleo Free Water Level. Impact on oil in place.
- Saturation Transition zones in carbonates can be fairly thick. Large saturation change between Swi and Swc (dry oil limit)
- Grid the geological model at the same scale as the simulation model. Upscaling is best performed at the geological model building level
We would like to make a notable mention to the three Keynote presenters listed below for their excellent presentations and for getting us rolling each morning in an excellent manner.
16th Feb – Matt Bratovich – President Elect SPWLA
17th Feb – Raymond Mitro – ADGM ZADCO
18th Feb – Fareed Abdulah – AGM Bab & Gas ADCO
Acknowledgement and congratulations go to those who won awards during the course of the topical conference.
16 Feb, Michel Rebelle Total
17 Feb, Habeeba Ali ADCO
18 Feb, David Allen Schlumberger
Best Young Professional:
Rifaat Al-Mjeni – Shell Oman
Dr Shawkat Ghedan – Petroleum Institute
|Thank you for attending the 7th SPWLA Annual Topical Conference. Please find the summary of your rankings of our efforts. The Abu Dhabi Chapter values your comments and strives to improve each year.|
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