MEM’s for HO-EOR evaluation


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Micro engineered machines for assessing heavy oil enhanced oil recovery strategies.

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MEM’s for HO-EOR evaluation

  1. 1. 200000 400000 600000 800000 1000000 1200000 1400000 0 10 20 30 40 50 60 70 80 90 100 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 + 1) Channel with bead trap 2) Channel packed with beads 3) Oil flown into channel 4) Water flown into channel 5) Volume of oil and water in draining wells counted 500  m Conventional core flood equipment The MEM for evaluating HO enhanced oil recovery is created using a method called pattern transfer. This is similar to the methods used for microchip manufacture. The basic component of the device is a small channel 500 by 40 micrometers in cross section designed to hold a sand-column upto 1mm in length. We have fabricated the device from sodalime glass so that it is chemically resistant and can tolerate high temperatures. The footprint of the device is 8 by 2 cm. Fluids are flown through a single channel of the device by positive displacement using syringe pumps During an experiment glass beads are introduced to the device prior to a 10 000 cp oil being emplaced. Water is circulated. The volumes of different fluids flowing through draining wells is recorded from video-stills. Use of chemical additives for HO-EOR A number of methods have been developed for heavy oil production, a subset of these use chemical additives to modify the properties of the water phase to enhance oil recovery. These generally involve making the water phase more viscous (so that it better displaces oil) and mobilising the oil (by surfacting oil in water or unbonding oil from the host formation). In this situation the key question is how much more oil can be recovered by a specific volume of the additive and will this be economic? Apart from field trials the only way to answer this question is to perform core-flood experiments. However these are difficult to set up and run because they require considerable resources and expertise. Unfortunately the information provided by these experiments is key to the basic Evaluation and Management of a heavy oil reservoir. This poster describes a micro-engineered-machine (MEM) that can be used to perform these measurements. <ul><li>Heavy oil Reservoirs </li></ul><ul><li>Heavy oil is viscous oil (> 10 000 cp - more sticky than treacle) and constitutes an increasing fraction of the worlds oil reserves. For any reservoir to be economic the cost of producing oil must be less than the commercial value of the oil. Several factors interact in heavy oil reservoirs to make them unfavourable economic prospects: </li></ul><ul><ul><li>1) The high viscosity of heavy oil relative to water causes water to move through reservoir more readily than water </li></ul></ul><ul><ul><li>2) Tendency to be oil wet – oil preferentially sticks to the host formation. </li></ul></ul><ul><li>Thus heavy oil reservoirs will produce with a high water cut early during field history and with a poor sweep efficiency (relatively little oil will be recovered per volume of water circulated). This impacts economic viability by adding additional costs as a function of the increasing volume of water that needs to be circulated and volume of water that needs to be separated from the oil. This cost can rapidly escalate in remote environments e.g. off-shore where space for seporators may be limited or where temperatures are sub-zero and water must be heated. </li></ul>One method of heavy oil recovery uses chemical agents added to water to increase oil recovery For a prospect to be viable the cost of the EOR must be less than the value of he oil produced water oil Introduction Methodology Progress so far: The project is at an early stage; so far the device has been successfully manufactured and realistic core flood experiments conducted. Both water- & oil-wet production profiles have been produced. In the next stages heavy oil recovery methods using a chemical agent (supplied by Glensol) and hot water will be trialled. 4 seconds 12 seconds 31seconds 76 seconds Time seconds cumulative oil produced 0 10 20 30 40 50 60 70 80 90 100 Time seconds fractional water cut 0 seconds 12 seconds 50 seconds 72 seconds cumulative oil production Fractional water cut cumulative oil production Fractional water cut Water-wet experiment Oil-wet experiment Results <ul><li>Only two experiments have been performed, but these illustrate that the device can be used to mimic both oil-wet and water-wet behaviour. </li></ul><ul><li>In the water-wet experiment “water break though” took twice as long as for the oil wet experiment. In the fractional water cut parameter this is evidenced by a 30 % instantaneous increase as opposed to a slower and lesser increase in the oil wet system </li></ul><ul><li>The water-wet experiment is characterised by piston like displacement. In the experiment this is observed as discrete slugs of oil or water exiting through the draining wells (compare this to the oil-wet experiment where water flows along one side of the well and oil through the other). </li></ul><ul><li>Much less oil was recovered during the oil-wet experiment, suggesting a higher irreducible oil saturation </li></ul>Future work <ul><li>Currently the experiments have been performed at very high flow rate with many pore volumes being circulated over a very short period of time. Performing these experiments at a range of flow rates is the most immediate priority </li></ul><ul><li>Performing the first experiments to simulate a range of enhanced oil recovery techniques (chemical additives & thermal methods). </li></ul><ul><li>Packing the channel with a range of materials, and varying grain sizes and shapes </li></ul><ul><li>Using purpose cut miniature cores </li></ul>Micro engineered machines for assessing heavy oil enhanced oil recovery strategies MEM’s for HO-EOR evaluation Stephen Bowden Geofluids Group, Dept. Geology and Petroleum Geology School of Geosciences, University of Aberdeen Aberdeen, AB24 3UE [email_address] £ MEM for heavy oil EOR