Method and apparatus for obtaining heavy oil samples from a reservoir sample

Abstract

The invention relates to an apparatus and method to obtain a bitumen or heavy oil sample from an oil reservoir sample, such as a core sample, to enable measurement of physical properties such as viscosity, API gravity, or chemical properties such as sulphur content of the obtained bitumen or heavy oil sample. The analyses performed on the samples obtained in accordance with the invention are effective in assisting oil field operators in making timely drilling and production decisions at the oil reservoir or for routine laboratory extraction of oils and bitumens. The invention also permits the collection of samples from simulated thermal recovery operations and also allows the collection of bitumens and oils for online analysis of live oil physical properties.

Description

FIELD OF THE INVENTION[0001]The present invention relates generally to an apparatus and method to obtain a bitumen or heavy oil sample from an oil reservoir sample, such as a core or drill cuttings sample.BACKGROUND OF THE INVENTION[0002]As the world's conventional oil reserves are being consumed, Heavy Oil and Tar Sands (HOTS) reservoirs are becoming increasingly important as a source of petroleum fluids. However, recovery of oil from HOTS reservoirs is generally difficult due to the high viscosity and poor mobility of oil, difficult production and high fluid property heterogeneity in reservoirs. Of the world's petroleum reserves (6 trillion barrels), most exists as heavy oil or oil sand (tar sand) bitumen. Currently, only an average of 17% of this oil can be recovered.[0003]In high porosity and permeability reservoirs, development strategy and production depends on fluid mobility, of which oil viscosity is a major controlling factor. Thus, assessing viscosity of oil throughout HOT...

AI Technical Summary

Benefits of technology

The method provides high-quality, sediment- and water-free oil samples that can be analyzed quickly, assisting in timely drilling and production decisions, with improved retention of low boiling components and reduced costs compared to existing techniques.

Problems solved by technology

However, recovery of oil from HOTS reservoirs is generally difficult due to the high viscosity and poor mobility of oil, difficult production and high fluid property heterogeneity in reservoirs.

Ideally, however, the viscosity should be measured directly on a live oil sample that contains the in situ gas content of the reservoir sample, which is mostly not possible due to limitations of the methods by which oil or bitumen is extracted from samples and by which viscosity measured.

Usually, solvents cannot be completely removed without losing some of the low molecular weight petroleum components within the bitumen.

Thus, viscosity measurements on solvent extracted bitumen are considered unreliable with existing procedures.

However, this method proceeds slowly due to the high viscosity of the petroleum in many samples and cannot be performed easily or quickly enough at the well-site.

Moreover, even if time is available in a laboratory the expense of engineering-rated centrifuges raises costs dramatically.

In addition, large quantities of reservoir rock (>0.5 kg or equivalent to a minimum of 30 to 50 cm lengths of slabbed 4″ core) are usually required to acquire adequate samples for fluid property determinations, which is both destructive and difficult to handle.

These techniques are both time-consuming and expensive or ineffective as often insufficient liquid samples are obtained for subsequent physical property testing.

At present, these slow mechanical laboratory petroleum recovery processes are a bottleneck in most bitumen or very heavy oil production planning operations.