Safety technology for pressure measurement of ther

The safety technology of pressure measurement of electric pump well

pressure data is very important for analyzing and mastering the underground situation of oil field and the production performance of electric pump well. These data must be taken completely and accurately to ensure the efficient operation of electric pump well. At present, there are three pressure measurement methods for electric pump wells in most of the original dressings:

(1) pressure measurement of motor tail monitoring devices (i.e., PhD, psi)

(2) pressure measurement of type III pressure measuring valve

(3) pressure measurement by dynamic liquid level conversion pressure method

phd or psi pressure measurement method is still in the experimental stage at present. Due to its short service life, it is less used in production. Due to the influence of the foam section in the annular space of the casing, the converted pressure value has a large error, and the application range is limited. Type III pressure measuring valve is a commonly used pressure measuring method at present. It can be used together with mechanical pressure gauge to measure the static pressure and flow pressure data of electric submersible pump wells, and the plug can be fished out to replace the oil drain valve during pump inspection

1. Structure and working principle of type III pressure measuring valve

type III pressure measuring valve is composed of working barrel, plug, connector and fishing device. The plug is installed in the working barrel and goes down to the well. The pressure measuring valve is closed by the sealing effect of the inner and outer packing. If necessary, it can be fished out of the working barrel with a fishing tool. During pressure measurement, the connector is connected with the test rod of the plug at the lower end of the pressure gauge, the spring is compressed by the weight of the instrument, and the test rod is positioned by the internal contact of the connector and the action of the spring. The 6mm transverse hole at the upper end of the test rod is connected with the transverse hole on the side of the connector butt joint. At this time, the oil pipe is connected with the casing. The pressure enters the central hole of the test rod along the 6mm hole of the working cylinder, the 4mm hole on the plug body, and the 6mm transverse through hole at the lower end of the test rod. Through the 6mm transverse through hole at the upper end of the test rod, it is transmitted to the circular space between the connector butt joint and the external fitting part, and enters the pressure gauge through the upper joint. After the pressure measurement, the gravity disappears, and the test rod automatically resets under the action of the spring to close the pressure measuring valve

2. Safety inspection and preparation before pressure measurement

check the firmness and reliability of the lubricator, derrick, guy wire, and the sensitivity of the pulley; Check the accuracy of the revolution meter and the integrity of the winch and steel wire. Check that the wellhead equipment has no leakage, and the gate switch should be flexible. Understand and master the pipe string structure of the tested electric pump well, the model and accurate depth of the pressure measuring valve, and the surface flow of the oil well

master the production performance, liquid production, oil pressure, casing pressure, water content and (1) return to zero difference before pressure measurement of electric pump well, which are the necessary inspection items for subsequent verification. If the wax deposition in the tested electric pump well is serious, contact the oil production team in advance to remove the wax first and then measure the pressure, so as to ensure the smooth lifting and lowering of the pressure gauge. Record all parameters taken before pressure measurement of electric pump well for comparison with the data taken after pressure measurement

3. Safety technology of on-site pressure measurement

(1) prepare a calibrated mechanical pressure gauge and a pressure measurement clock, a 0.5m-long weighting rod, a rope cap, and testing tools

(2) check the interference of the connector packing with an 18mm stick, and use the adjusting nut to make the interference meet the requirements

(3) connect the weighting rod, pressure gauge (without shock absorber) and connector from the rope cap in turn

(4) open the lubricator plug, put the installed pressure measuring instrument, open the wax removal gate, calibrate the revolution meter, and send the pressure gauge underground with the winch. Pay attention that the lowering speed should not be too fast, preferably 0.8m/s, and avoid twisting the steel wire

(5) when the pressure gauge is lowered to 5 ~ 10m above the working cylinder of the pressure measuring valve, stop for 5min to measure the flow pressure of the oil pipe, and then continue to lower (the speed should be kept stable, not too fast, preferably 0.5m/s). Stop for 5 ~ 10min after sitting on the working cylinder, and the measured pressure at this time is the casing flow pressure. In order to ensure the success rate of the test, it is generally required to repeat the test for more than 3 times. Finally, lift 100m and stop for 5min to measure the tubing flow pressure gradient