SU149371A1 - A device for downhole determination of saturation pressure and compressibility factor of reservoir oils - Google Patents

Description

BASIC Auth. St. 126824, a device for downhole determination of saturation pressure and compressibility factor of reservoir oils is described, which contains a deep self-sensing pressure gauge, a chamber for sampling and investigation of reservoir oil, and a time relay.

In the proposed device, the receiving cavity is made in the form of a single chamber with an opening for draining the liquid with a specific gravity than the plastic layer. This simplifies the design of the device and increases its reliability.

The drawing shows the design of the proposed device. The device consists of a deep self-scanning manometer /, a chamber 2 for taking and examining a reservoir and an efti and a time relay. The chamber 2 for taking and examining the reservoir fluid contains a manometric chamber 3, an intermediate body 4, a connecting pipe 5 provided with openings 6, a polished brush 7 with a sleeve 8, a rubber self-sealing ring 9, a moving device 10, a polished brush 11 with windows 12 and a rubber self-sealing ring 13.

The time relay contains a connecting body 14 with a window, a piston 15, an oil chamber 16 provided with a capillary orifice 17, housings 18 and 19, rubber self-sealing rings 20, 21, 22, ballistic chambers 23, 24, polished brush 25 fitted with windows These 26, 27, the screw 28 and the housing 29, which serves to accommodate the clock mechanism 30.

When preparing the device for operation to the depth gauge 1 from the bellows side, the chamber 3 is screwed on, which is pre-filled with water. Chamber 2 of the selection and study of reservoir fluid No. 149371-2 -

pour a solution with a higher specific gravity (1.2-1.6) than the reservoir oil (0.9), and turn on the mixing device 10. The piston 15 with the rod 11 is pulled to its extreme upper position. Cavity chamber 16 and Cornus 19 is filled with oil. Rotating the screw 28, set the rod 25 to its highest position. Compressed air remains in the cavity of the chambers 23, 24. In the housing 29 install the clock mechanism 30.

When the device is introduced into the well, the oil through the holes 6 of the connecting tube 5 tends to get into the cavity of chamber 2, but this is hampered by the fluid located there. The rod // is in such a position that the lower end of the device is closed and liquid cannot escape. The piston rod 25 is prevented from moving the piston 15 to the lower position. The self-sealing ring 21 prevents the oil from falling from the cavity of the chamber 16 under the action of pressure into the cavity of the chamber 23.

When the device reaches the bottom, the clock mechanism 30 begins to rotate the screw 28, which draws the rod 25 into its way. A window 27 on the brush exits the rubber ring 21. The oil rushes through the gap between the ring 21 and the window 27 of the rod into the cavity of the chamber 23 with compression by air. As a result, the piston 15 moves downward by an amount depending on the volume of the cavity of the chamber 23. Simultaneously with the movement of the piston 15, the brush 11 moves, thereby opening the lower opening of the device, as the window 12 enters the ring 13. Thus the cavity of the chamber 2 is hydraulically connected With a borehole, two holes are top and bottom.

Due to the specific gravities of the solution and oil, the liquid flows out of chamber 2, and the reservoir is filled with oil. The rate of replacement of fluid with reservoir oil from the proposed device is 7-10 minutes. For safe operation, both openings remain open for 40 minutes.

After this time, as a result of the continued movement of the rod 25, the window 26 enters the ring 22 and opens the cavity of the chamber 24. Accordingly, the piston 15 with the brush // will go down and the window 12 will exit the ring 13. When the upper edge of the window 12 enters the ring 13 at the same time, the upper edge of the recess 5 will enter the I ring, as a result of which there will be a hydraulic isolation of the cavity of chamber 2 where the formation fluid is collected from the well. Further movement of the stem 11 will cause an increase in the volume of the chamber 2 by the amount of the stroke of the rod, which in turn will cause a drop in pressure. When the pressure drops below the saturation pressure, gas will be released from the oil. The mixing device 10 is switched on. The change in pressure in cavity 2 is sensed by a self-recording manometer helix. Coefficient of compaction of the reservoir fluid y „dr-g ,, where AF-

volume increment; DR - pressure difference; initial sample volume.

The gas factor and the volumetric magnification coefficient of the instrument are determined by degassing an oil sample in the cavity of the chamber, for which a sample sub is wrapped around the instrument and a glass separator connected to it is not shown on the drawing. The volume of gas emitted is measured with a gas clock, also not shown in the drawing.

The measurement of the measured volume of gas to normal conditions (pressure 760 mm Hg, temperature 20 °) is made according to the formula:

p r oo

y u .i.

DI /

760 273 -d

where / is the gas volume over the meter; Pgap-barometric pressure; PSH - water vapor pressure; t is the ambient temperature. The volume of gas remaining in the device also leads to normal conditions according to the formula:, where VQ is the chamber volume

Pribora.The total amount of gas emitted from oil.

The amount of remaining oil is determined experimentally by pouring a specific volume of oil into a clean device, followed by releasing the device from oil and re-determining its volume.

The solubility coefficient is K-, where P „is the saturation pressure, the gas factor Q, 1 /„ is the volume of degassed oil.

Volume increase factor b -, where - chamber volume

the device at the bottom after filling it with oil.

Subject invention

A device for downhole determination of saturation pressure and compressibility factor of reservoir oils according to ed. St. No. 126824. distinguished by the fact that, in order to simplify and increase the reliability of the instrument, the receiving cavity in it is made in the form of a single chamber with an opening for draining a fluid with a higher specific weight than formation oil.

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