SU956777A1 - Method of sampling deep-well liquid with gas dissolved in it - Google Patents

Description

The invention relates to the exploration and exploitation of gas and oil, in particular to hydrogeological studies of wells, and can be used. Used in the gas and oil industry.

To preserve the physicochemical properties of the samples, mainly the gas factor, they are taken at a bottomhole pressure equal to the reservoir pressure. During the recovery of the sampler from the well, the pressure in its chamber drops depending on the temperature gradient, thermobaric properties of the fluid and the sampler, and the speed of its rise. Especially great: pressure reduction in deep wells, where, as a rule, formations with abnormally high formation pressures occur. As a result of the well pressure exceeding the pressure in the sampling chamber, the latter may become depressurized and the sample will be distorted.

The most unfavorable lifting area is the final one, since when the sampler is located in the lubricator, its temperature decreases most of all, approaching TeNtnepaType of the outside air.

A known method of sampling a liquid with a dissolved gas using a sampler c. isotope heat source 1.

The disadvantage of this method is the increase in costs associated with the need for radiological protection. In addition, this method does not regulate the degree of heating that

10 leads to a distortion of the temperature of the fluid in the wellbore and does not guarantee quality testing.

There is also known a method of sampling a liquid with a dissolved gas at

15 assisting the sampler with an electric heater on the cable by lowering the sampler into the well, sealing the sample under bottomhole conditions, equal reservoir, and lifting it to the surface while maintaining the temperature that ensures that the pressure inside the sampler exceeds the well.

Downhole at downhole

25 pressure equal to the reservoir, lower the sampler and seal the sample. The rise is carried out with maintaining the temperature inside the sampler equal to the bottomhole, for which the sample

30 are heated with the help of ale

device that provides excess pressure inside the samplers over the well.

This method is used only in shallow wells with low bottomhole temperatures (up to) and a slight overpressure (23 MPa) 2. .

The disadvantage of this method lies in the fact that to descend the samplers on the cable into deep wells (with an overpressure of up to 100-110 MPa) requires the installation of bulky, 9-10 m long lubricators, which leads to costs for their installation and increases . In addition, it is necessary to create a powerful thermal protection to ensure the operation of the electronic circuit for regulating and maintaining the temperature, since at temperatures of 200-220 0 Normal equipment is unsuitable, which ultimately leads to a sharp increase in the cost of the process.

The aim of the invention is the simplification and accelerated selection.

The postlabeled goal is achieved by maintaining the temperature by starting the well. operation, and the sampler is lifted at a wellhead pressure below the pressure in the sampler at this point.

When carrying out the method, the task of raising a single-phase sample is not posed, since the sampler is degassed at the mouth to determine the gas factor. Lifting a single-phase sample will require ensuring the strength of the shell corresponding to the plastic pressure, which is unjustifiably necessary {T work. . ;

In the practice of research, the rise of samples from a well with a bottomhole pressure of 75-90 MPa is provided by a sampler of the brand PD-3M.

To ensure the integrity of the sample, it is sufficient that the well pressure does not exceed the pressure inside the sampler by the amount of elastic force of the spring (in a PD-3M sampler, it is 0.30, 5 MPa). The pressure inside the sampler must exceed the well pressure to guarantee the safety of the sample when the spring is out of operation, for example, due to corrosion.

The upper limit of the pressure drop is limited by the strength of the sampler body and depends on its geological and technical characteristics (the PD-ZM sampler is designed for a pressure of 30 MPa).

Example. Hydrogeological studies of a well with a depth of 5200 m are carried out with a S8V8 Sha reservoir pressure, temperature, hundred gauge pressure.

 MPa, wellhead temperature of 20 ° C, fresh reservoir water, background gas and a factor of 0.3 (minimally encountered on empty traps).

Descend to the bottom of the sampler with a capacity of 1000 cm (at a temperature). A depth test is taken and the well is put into operation through a seven-millimeter fitting.

0 With a debit of 500 Muss through

1.5 hours of wellbore wellhead temperature reaches, an overpressure of 9.0 MPa. Next, the ability to save the sample and

5 lifting the sampler in these conditions.

The volume of the sampler in the downhole conditions at the time of sampling is determined by the formula

 Vo (1 -ocd),

V.

305

where Vjgg is the volume of the sampler in the bottomhole conditions, VQ is the volume of the sampler in

laboratory conditions, cm; 5 0 - thermal coefficient

change in the volume of the sampler (for the sampler brand PD-ZM is 5, .10-51 / s)

0 & - temperature difference between laboratory and well conditions.

The compressibility of the robber collector is neglected, since it is 5 in total, about 0.05% of the original volume.

The volume of the sampler, and therefore the selected sample

 1000 1 + 5. (160 - 20)

V.

-50 (5,107 (cm).

water wellness in bottomhole conditions limit k) t according to the formula

and,

 -fiP {uo, 01b)

where rzoB density of the bone in the bottomhole conditions, g / cm, p is the degassed density

liquids, g / cm) DRO - change in density for

dissolved gas count

P - degassed water ratio, 1 / lftla)

Р - well pressure, MPa, b - gas factor,,

P 0.9076 - 8,: 84.10 0.3

w r r-tmiFrsM (1 + &, H1 0.5 .0.9383 (g / cm).

Next, determine the mass of the sample taken:

 Pr} goB GAB 0 .. (OOG.) 44.8G (g).

Claims (1)

'Claim Method for taking in-depth samples of a liquid dissolved gas by lowering the sampler into the well, sealing the sample at. 30 bottomhole conditions, equal to the reservoir, and lifting it to the surface while maintaining a temperature that ensures that the pressure inside the sampler is above the borehole pressure, about t 'l and -. 35, which, in order to simplify and accelerate the "sampling, the temperature is maintained by putting the well into operation, and the sampler is lifted at 40 'pressure at the mouth below the pressure in the sampler at this point.