A feature of an oil field is the ability to conduct production from different rock layers in one well. In order to separate individual layers, packers are applied. A packer consists of several independent areas allowing you to selectively seal individual sections of the well and, thereby, conduct production at certain strata. Unlike cementing and clay pills, the packer provides temporary isolation of the horizon and allows you to quickly restore work in any part of the well.
Rubber sleeves are the main part of the packer. They are massive rubber items that seal the wellhead. The sealing effect is achieved due to sleeve expanding under pressure. After depressurization, the sleeve returns to its original state. In this regard, the following mandatory requirements apply to the rubber sleeves of the packer:
- Maximum resistance in direct contact with oil.
- Resistance to sudden changes in temperature. The upper limit of the operating temperature range is 1500C.
- Resistance to sharp pressure drops. The upper pressure limit is 70 MPa.
- Resistance to abrasion.
- Minimum rates of compression set. After removing a long load, the sleeve must return to its original state. Failure to comply with this requirement leads to an emergency shutdown of the well.
Types of packer sleeves
- Dissociative – used to work at different horizons, ensuring the separation of produced oil from each stratum without mixing. They are also used for the simultaneous production of oil and gas;
- Bottom-hole – endowed with shut-off valves that prevent oil gushing due to high pressure in oil-bearing strata;
- Isolating – used to isolate the annulus in an oil well, due to which oil rises exclusively through pipes.
Types of rubber compounds used
|Nitrile butadiene||NBR||Resistant to gasoline, diesel and mineral oils.||from -55 to +1350C|
|Hydrogenated nitrile butadiene||HNBR||The same properties as in nitrile butadiene rubber, but the upper limit of the operating temperature range is higher. Somewhat higher elastic qualities. Increased resistance to aging in the air.||from -55 to +1650C|