Analytical Techniques and Tools for Rock Property and Oil Gravity Evaluation in Heavy-Oil and Tar-Sand Reservoirs
Published:January 01, 1987
B. A. Bell, K. Karnes, 1987. "Analytical Techniques and Tools for Rock Property and Oil Gravity Evaluation in Heavy-Oil and Tar-Sand Reservoirs ", Exploration for Heavy Crude Oil and Natural Bitumen, Richard F. Meyer
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Knowledge of the procedures and techniques currently used for rock and oil analysis will increase the qualityofinterpretations made on data generated.
There are two basic techniques used to measure porosity, permeability, and saturation data. One involves retorting or high temperatures and the other a distillation process. Specific procedures used in these analyses willvary depending on the formation type encountered. Formation types can be placed into one of three categories that will decide procedures used. These categories are consolidated, unconsolidated, and shale. Procedures also vary within these categories to accommodate conventional cores, sidewall cores, and drill cuttings samples.
The quality of data generated in the analysis for API oil gravity is dependent on both the source of the sample and the procedure used. Once an uncontaminated sample is obtained its API can be determined by refrac- tometer, float method, electronic densitometer, hydrometer, or pycnometer.
There are advantages and disadvantages to procedures used for both rock and oil analysis, which should be evaluated to accommodate the needs of the project.
Figures & Tables
Exploration for Heavy Crude Oil and Natural Bitumen
Gross volumes of oil, which must be kept in mind to address the volume/size framework, may be thought of in order from largest to probably smallest volumes as follows: (1) generated; (2) dissipated; (3) degraded/ partially preserved; and (4) trapped and conventionally producible. Basic knowledge of these volumes may be from greatest to least in essentially reverse order.
The 332 largest known accumulations (less than 1% of the total number) account for more than three-quarters of the known 7.6 trillion bbl of oil and heavy oil or tar in more than 40,000 accumulations in the world. About 2.4 trillion bbl of estimated undiscovered conventional oil added to the known volume of 7.6 trillion bbl yields a total of 10 trillion bbl known or reasonably estimated. World-wide cumulative production of about 500 billion bbl of oil accounts for only 5% of the gross.
Oil in place must be estimated for conventional oil fields before comparison with heavy oil and tar accumulations. The size range of accumulations considered in the size distribution of the 332 largest known accumulations is from 0.8 to 1850 billion bbl of oil. The smallest conventional fields in the distribution are about 1 billion bbl because the size cut-off is 0.5 billion bbl of oil recoverable. The size distribution of the 332 largest known accumulations approaches log normal and is overwhelmed by the largest three supergiant tar deposits that hold nearly half of the total 5495 billion bbl.
Globally, the largest three accumulations, all heavy oil or tar, are in South and North America; the two largest conventional oil fields are in the Middle East. Prudhoe Bay and East Texas fields rank 18 and 34, respectively, in descending size order.