RU2389872C1 - Pressurisation and survey method of oil and gas wells - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: pressurisation and survey method of oil and gas wells includes lowering of the tool to the well, attachment above the top of formation, measurement of pressure in the area under the packer, and recording of readings in real time mode. Test pressure from the head is created and column tightness is determined. At the same time, there performed is additional measurement of pressures, dynamic of change of temperature and flows of well liquid in the area above the packer by installing pressure sensors and thermal conductive indicator in the area above the packer, and flow metre on the well head. Further comparison and calculation of the obtained parametres is performed. At that, if the parametres are stable, it means that there are no interruptions in the well, and when the obtained parametres are instable, it means that there are interruptions in the areas above the packer and below the packer. Packer is removed and the tool is arranged in the other interval of the well with further measurement of data.

EFFECT: increasing resolution capability at simultaneous reduction of time required for the well survey, improving accuracy of determination of column and intervals of available interruptions, eliminating emergency situations.

2 cl, 7 dwg

Description

The claimed technical solution relates to the oil and gas industry and can be used for pressure testing and well research, as well as for overhaul and maintenance of wells.

A known method of pressure testing and research of oil and gas reservoirs, including the descent into the well of the device, landing above the roof of the reservoir, measuring pressure in the under-pocker zone, recording real-time indicators, creating test pressure from the mouth and determining the tightness of the column, which is carried out using a universal packer crimping and research of columns (RF patent No. 2268988, IPC ЕВВ 33/12, ЕВВ 47/00, publ. 2006.01.27).

The disadvantage of this method is the low resolution for detecting violations with low injectivity (less than 400 l / h), the high complexity of the method (high material and time costs), sudden pressure drops leading to emergency situations (cable break), the inability to clearly identify with one measurement type of violation.

The objective of the claimed technical solution is to create a method that provides pressure testing and investigation of wells and reservoirs, identifying and identifying violations in wells and reservoirs in one run of the device.

The problem is achieved due to the fact that in the method of pressure testing and research of oil and gas wells, including the descent into the well of the device, landing above the roof of the reservoir, measuring pressure in the under-packer zone, recording real-time indicators, creating test pressure from the wellhead and determining the tightness columns, new is that at the same time they additionally measure pressures, dynamics of changes in temperature and flow rates of well fluid in the overpacker zone by installing pressure sensors and thermoconductive indicator in the above-packer zone, and the flowmeter at the wellhead, carry out subsequent comparison and calculation of the obtained indicators, while in the presence of stable indicators they judge the absence of disturbances in the well, when receiving unstable indicators they judge violations in the over- and sub-packer zones of the reservoir and well , perform unpacking and landing of the device in another interval of the well with subsequent measurement of data.

Measurements of well fluid pressures in the over- and sub-packer zones and flow rates of well fluid in the over-packer zones in wells with absorbing formations or with low reservoir pressures with a pressure difference in the indicated cavities of 3-5 atmospheres are carried out after pressure equalization, with a pressure difference in the indicated cavities more 3-5 atmospheres produce a smooth pressure relief; when the pressure readings in the indicated cavities are equalized, the packer is disrupted.

The method is carried out by means of a device for pressure testing and well research (POIS-K) (RF application No. 2006141929). The claimed technical solution is characterized by figures 1-7. Figure 1 presents the device for crimping and research wells. Figure 2 shows an example of violations over the packer (two violations). Figure 3 shows an example of violations over the packer and in the packer. Figure 4 shows an example of violations in the packer (two violations). Figure 5 shows an example of violations under the packer (two violations). Figure 6 presents a summary diagram No. 1 of the detection of disturbances in the well.

Figure 7 presents a summary chart No. 2 of the study well. The device for crimping and researching wells (see Fig. 1) consists of a hollow body 1 in which a pressure sensor 2 is located, which measures the hydrostatic pressure above the device, a temperature sensor 3, a thermoconductive indicator sensor 4, a coupling locator sensor 5, an electromechanical packer 6, having an electric motor 7, a gearbox 8, a nut 9 and a screw 10 forming a screw pair for converting the rotational moment of the electric motor 7 into axial force, a central rod 11 connected to the screw 10 in the upper part, and in the lower part connected to the push Lemma 12, partitions 13 with O-rings 14 and directly the packer 15, having a cone 16 with movable dies 17, fixed 18 and movable 19 flanges, a rubber sleeve 20 located on the stationary nozzle 21, a movable sleeve 22, a saddle 23 and o-rings 24 located on the central rod 11, forming a controllable valve, emergency washer 25, nut 26, a pressure sensor 27 located in the central rod 11 and through the channel 28 in communication with the under-packer space, the processing unit and the issuance of research results 29 located on the geophysical elevator 30, the cable rope 31, and the processing unit with the results display panel 29 and the control panel 32, the fluid flow meter 33 and the pressure sensor 34 located at the mouth of the liquid filling line 35, wellhead sealant cable 36.

The method is as follows.

A device for crimping and researching wells is lowered into the well on a cable rope 31, while a pressure sensor 2, a temperature sensor 3, a thermoconductive indicator sensor 4, a coupler locator sensor 5 are put into operation through the information processing and output unit. The information received from the sensors is recorded in block processing and issuing research results 29 and is displayed on a computer monitor in real time.

The device goes down to the top of the reservoir and the packer 15 is planted to the column and the cavity of the well is divided into two parts - the upper I and lower II (see figure 2).

To do this, the direct polarity current is supplied from the control panel 32 to the electric motor 7, it transmits torque through the gearbox 8 to the nut 9, the screw 10 moves up, the central rod 11 moves up with it and the pusher 12, in turn, the pusher 12 moves up the dies 17 along the cone 16 in the vertical and horizontal directions that are fixed to the wall of the column, then the housing 1 moves down, the movable flange compresses the rubber sleeve 20, because the movable sleeve 22 sits on the stationary nozzle 21. The rubber sleeve 20 is deformed in the transverse direction of the section and overlaps the wellbore, while the o-rings 24 extend into the seat 23 and hermetically close the movable joint of the central rod 11, forming a valve. Thus, the packer 15 tightly seals the upper cavity I from the lower cavity II.

After the packer 15 is fixed to the column, the readings are taken from all sensors on the processing unit and the results of the study 29 are output. The well is filled with liquid from the wellhead using the CA-320 unit, the wellhead sealant 36 tightly presses the cable-rope 31 and pressure is created in the cavity I - P _def .

The pressure in the cavity I is controlled by a pressure sensor at the mouth 34, the fluid flow is controlled by a fluid flow meter 33.

If the column is not tight, then the pressure in the cavity I will fall, because through violations in the column, the liquid leaves the column, which will be shown by the sensor (see Fig. 6, section a ₁ -b ₁ ) of pressure 34, the liquid flow meter 33 will show how much liquid Q ₁ passes through the existing violation (see Fig. 6, plot d ₁ -d ₂ - line flow of fluid at the mouth). A pressure sensor 27 located in the central stem 11 will indicate the pressure under the packer, i.e. in cavity II (Fig. 6, section P ₁ -P ₂ is the hydrostatic pressure line under the packer), if the packer 6 is sealed tightly, then the pressure under the packer will be constant, the hydrostatic pressure line under the packer is horizontal, if the packer is not sealed tightly, then the diagram will show the sloping line of hydrostatic pressure under the packer at P ₁ -P ₂ .

To detect (search) the violation interval, the packer breaks off the column, for this, the reverse polarity electric current is supplied to the electric motor 7 from the control panel 32, all the details of the electromechanical packer 6 begin to work in the opposite direction. Packer rubber 20 restores its original shape, dies 17 extend from the walls of the column, the electromechanical packer breaks off the column and sits higher on h ₂ . On the chart No. 1 (see Fig.6) shows the readings of all sensors

When the violation appears in the registration area, i.e. between the packer 15 and sensors 2, 3, 4, 5, where the distance is 1.5 meters, when pressure is created in cavity I, temperature sensors 3, thermoconductive indicator 4 show the dynamics of temperature change, and the liquid flow meter 33 at the mouth shows the amount of absorbed liquid Q ₂ , and the manometer 34 shows the pressure drop in the cavity I, in the area a ₂ -b _{2 of the} chart No. 1 (Fig.6) shows the violation interval h ₂ . To determine the boundary of the violation, the packer again breaks down and lands above (see Fig. 4), in the interval h ₃ , again, by creating pressure in the cavity I using the CA-320 unit, the intervals of violations are specified when the second violation falls into the registration zone (see Fig.6, diagram No. 1, plot a ₃ -v ₃ ).

The liquid flow meter 33 at the mouth shows the amount of absorbed liquid Q ₃ through violation 2, which is much less than in the previous interval h ₂ , which confirms the presence of the first violation.

Q ₁ -Q ₂ -Q ₃ + Q '₁;

Q ₁ '= Q ₁ -Q ₃ ;

where Q ' ₁ is the amount of absorbed fluid through I violation.

Also, the pressure drop rate is lower in the range of h ₃ (see FIG. 6), sensors 2, 3, 4 confirm this violation. Thus, by pressing at intervals along the entire height of the well, all existing violations are determined. The degree of accuracy of the detection of the violation interval is ± 0.75 m, because the distance between the packer 15 and the sensors, which is the zone of registration of the violation, 1.5 m

Diagram No. 2 (see Fig. 7) shows the operation of the device in wells with absorbing layers or with low reservoir pressures, where it is impossible to examine the well with previously used technical means (1) and (2).

In such wells, the device first descends, the packer 15 is placed on the column, only after that the well is filled with liquid (cavity I), the research and pressure testing technology remains the same (see figure 2, figure 3, figure 4, figure 5) . The process of disruption of the packer is as follows.

Before opening the adjustable valve, the readings of the pressure sensors above the packer 2 and below the packer 27 are compared, if the difference is 3-5 atmospheres, then the control valve can be opened to the end, thereby balancing the pressure in cavities I and II, and then the packer will be disrupted . And if the difference is much greater than 3-5 atmospheres, then at the beginning the control valve opens slightly, while it is necessary to monitor the decrease in pressure in cavity I by pressure sensor 2 and wait for the readings to align with pressure sensor 27 located under the packer. After equalizing the pressure in the cavities I and II, the packer is disrupted, which eliminates the breakage of the cable rope 31.

To clarify the type of violations, for example, if it is necessary to localize violations with low injectivity, there is a need for additional studies through the use of other devices, these operations are associated with additional preparatory work at the well and lead to a significant increase in the cost of work (the hourly cost of a team of three people costs about 2700 rubles., Thus, re-examination of the well per day during three-shift work costs about 2700 rubles. * 24 = 64800 rubles.).

The claimed method has the following advantages compared with the closest analogue:

- has a high resolution to detect violations with low throttle response (less than 400 l / h), including due to the use of the well-known borehole thermoconductive indicator in the upper part of the device;

- does not require large expenses for well preparation and its multiple studies;

- allows you to control violations in the well for one lowering of the device;

- eliminates emergency situations, for example, cable breakage (at a pressure in the reservoir of 60-80 atm under the packer, and above the packer at 100 atm) when working in the well at great depths with low reservoir pressure by controlling the reduction in pressure drop above and below the packer through the processing unit and issuing the results of the study in real time, and conducting a number of additional measurements, taking readings of the sensors, including additional sensors of the thermoconductive indicator and pressure located above the packer;

- provides the ability to uniquely identify the types of violations in a single measurement, for example:

a) loose packing of the device in the well when the device hits the pipe joint, in the leaky section,

c) when the packer enters the area with any contamination,

d) a small depressurization of the well above the packer.

Claims (2)

1. The method of pressure testing and research of oil and gas wells, including the descent into the well of the device, landing above the roof of the formation, measuring pressure in the sub-packer zone, recording real-time indicators, creating test pressure from the mouth and determining the tightness of the column, characterized in that at the same time make additional measurements of pressures, dynamics of changes in temperature and flow rates of well fluid in the overpacker zone by installing pressure sensors and a thermoconductive indicator in the overpacker zones and the flowmeter at the wellhead performs a subsequent comparison and calculation of the obtained indicators, while in the presence of stable indicators they judge the absence of disturbances in the well, when receiving unstable indicators they judge violations in the above- and sub-packer zones of the formation and the well, unpack and plant the device in another interval of the well with subsequent measurement of data. 2. The method according to claim 1, characterized in that the measurement of the pressure of the well fluid in the above- and sub-packer zones and the flow rate of the well fluid in the above-packer zones in wells with absorbing layers or with low reservoir pressures with a pressure difference in these cavities of 3-5 atm they are carried out after pressure equalization, when the pressure difference in the indicated cavities is more than 3-5 atm, a smooth pressure relief is performed, when the pressure readings in the indicated cavities are equalized, the packer is disrupted.

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