Circulating and pressure equalizing sub
US4427070A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 29, 1982 |
| Grant date | Jan 24, 1984 |
| Priority date | — |
| Expiry date | Mar 29, 2002 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T137/1782
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A circulating sub is provided which is adapted for connection in a production tubing string of a flowing well and which defines a flow passage through which production fluid is enabled to flow. The body structure of the sub defines an equalizing port in communication with the annulus between the tubing and casing of the well, which port is normally closed by means of a sleeve valve. An actuating plug is dropped through the production tubing after shutting in the well and descends to the level of the circulating sub where it seats on the closed valve. Application of fluid pressure through the tubing develops sufficient pressure differential across the valve and plug to force the valve to its open position to thus communicate the tubing and annulus for pressure equalization. The plug member incorporates a check valve which permits accurate balancing of kill fluid to well pressure to thus permit emergency killing of the well without causing damage to the production formation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.