Frozen temporary plugging technology is a new technology introduction of Canada SNUBCO company, it can carry out the casing annulus and tubing nozzle temporary plugging, the wellhead pressure drop to zero, set, can achieve change wellhead No. 1, No. 2, No. 3 gate of the objective. In the surface casing is installed around the frozen box, add refrigerant, and then through the refrigeration system with hydraulic special temporary plugging agent layer into the interior of each layer and the tubing casing annulus (if annulus cementing have been filled with cement or water do not need to inject temporary plugging agent), frozen for some time, then can also be a multilayer casing annulus and tubing diameter temporary plugging. The following the main features:
1) can be at ambient temperature under the condition of -35~+50e, at the same time, temporary plugging internal multilayer casing annulus and tubing.
2) temporary plugging success, high safety factor, if you stay in the coolant in the freezing box, temporary plugging will always keep the temperature around -70e.
3) blocking convenient, demolition of refrigerant, man-made or natural temperature heating plugging plugging, otherwise would have been in a state of temporary plugging. Temporary plugging agent can be discharged through the discharge jet, gas recovery.
4) temporary plugging of high pressure, the maximum working pressure of 70 MPa. Temporary plugging, reverse test pressure at least 2 times the shut in pressure to pressure test.
5) tubing and casing safety coefficient is derived theoretically, scientific and reliable. When the temporary plugging agent in downhole throttling formed after the bridge plug, the formation of the throttle pressure difference in the bridge plug at both ends, the pressure in the temporary plugging agent to produce the corresponding force, size and the throttle pressure difference is proportional to the force.
