News

According to the requirements of the development plan, perforating is to use a special oil well perforator to penetrate the casing wall and cement ring barrier of the target layer to form the connecting hole between the target layer and the casing wellbore. Therefore, perforation is an important step of oilfield development and an important means of oil, gas and water production.

1.the working principle of magnetic positioner

It is known from the law of electromagnetic induction that when the magnet or coil is in relative motion, the magnetic flux of the magn

etic field around the coil changes, the magnetic wire cuts the coil turns and generates the induced potential and induced current, the coil is not a loop, there is no induced current, only the induced potential exists. The basic condition of electromagnetic induction is the magnetic wire-cut coil of the magnetic field surrounding the coil, and to make the magnetic wire-cut coil, the magnetic flux of the magnetic field around the coil must be changed. That is, the magnet and the coil are in relative motion, but the structure of the magnetic positioner does not allow the magnet and the coil to be in relative motion, then the magnetic flux around the coil will not change, and it will not generate induction potential, so that we can use another form of magnetic flux change, that is, relying on foreign ferromagnetic material changes. The induced potential generated by the external ferromagnetic material affecting its own magnetic field reflects the changes in the external environment. Therefore, when the magnetic locator glides through the collar in the casing, the magnetic field line distribution changes due to the change in the thickness of the external ferromagnetic material – the casing wall, so that the induction potential is generated by cutting the coil. When the magnetic locator signal waveform is being recorded on the surface instrument, it will be determined that the magnetic locator is passing through the collar at a certain depth in the well. Thus, it can coordinate with the depth part of the ground instrument to complete the perforation positioning work.

2.Comply with perforating site operating procedures

(1)Kill well according to the requirements of the design scheme.

(2) Prepare the wellhead equipment and installationtools to effectively prepare for blowout prevention.

(3) Before perforating, the casing must passthrough the well according to the regulations, sand washing the well to the artificial bottom of the well.

(4) Casing pressure must be tested and complied with before a new well is perforated.

(5) The perforation depth error shall not be greater than 0.1m.

(6) If the perforation meter exceeds 3m,the well can be completed only after the pipe string is washed.

(7) The liner well must be tested after perforating, the extrusion volume is greater than 1m³, the extrusion pressure is less than 15MPa, and the extrusion time is not less than 5min.

(8) During the perforating process,there should be a special person to take care of the wellhead, prevent falling objects, and pay attention to whether there is oil and gas display. If overflow is found, the perforation should be stopped, the pipe string should be seized immediately, and the liquid column pressure should be adjusted before perforating.

(9) In the process of cannonball, ifthere is resistance, do not be hard, must put forward the cannonball, and take corresponding measures after studying the underground situation.

(10) During the entire construction process, the workover team must work closely with the perforating team to achieve safe perforation, and no fireworks are allowed around the wellhead.

(11) Perforation data collection:

① Review perforation construction cards;

② Measure the density of kill fluid;

③ The perforating method is both gun type;

④ Open formation, well interval, number of holes, emissivity;

⑤ What is displayed after perforation;

⑥ Perforating time and running order;

⑦ Other special circumstances.