Patent Application
20150129218
The field of this invention is fracking in completions where the liner needs to have a pressure integrity test or internal pressure applied and objects need to be pumped to a desired location through a flow path established after the pressure application.
As regulations regarding completions become more restrictive due to safety and other reasons a need has arisen to perform a pressure integrity test on a string in a variety of circumstances. The string could be cemented and need to have a series of bridge plugs and perforating guns delivered at different depths so that portions can be sequentially perforated and fracked. However, with a need for a pressure test on the tubular there needs to be no openings in the wall open. In order to then be able to pump bridge plugs attached to perforating guns after a pressure test particularly in a horizontal well defined as having an incline of more than 62 degrees from vertical there has to be a wall opening through which circulation or injection can be established where the ported sub that can provide such an opening is configured to stay closed during the pressure test of the string. The problem is that if the ported sub opens in response to applied internal pressure, the needed pressure to get the ported sub to open after the pressure test of the tubular will require subjecting the string to even higher pressures to open. In other fracking systems a series of packers that are spaced apart are set at the same time before any fracking sleeves are opened up. The problem here is that if a pressure test is required on the string and the packer setting ports are still open then the packers will be subjected to higher pressures than the intended setting pressure. This additional setting force on the packers can adversely affect the formation by fracturing at the packers rather than as intended between them. Accordingly it would be advantageous to be able to pressure test the string without the packers set and then set the packers without having to further resort to even higher pressures than the pressure integrity test on the tubular string.
The method of the present invention relies on ported subs that can be selectively opened with a timer or a signal. In the case of multiple spaced packers, the string can be pressure tested without the packers being set. The setting force for setting the packers can be annulus pressure so that valves can communicate annulus pressure to an actuation piston for the packers to set them with a reference pressure on the opposite side of the piston as being low or atmospheric. The order of setting can be as desired and the valves can respond to a timer or another signal for operation to set the packers in the desired order. Then in order to be able to deliver a succession of balls to different frack sleeves between pairs of packers a ported sleeve valve can be triggered by timers or other signal to open a first access to the formation so that all balls that then need to land on seats and shift sleeves for formation access can be pumped because there will always be a flow path for fluid to carry each ball to its destination.
Relevant to the art of using timers to shift sleeves or operate other downhole equipment are: WO2009/105128A1; U.S. Pat. No. 4,709,708; 6,035,880; 3,896,667; 3,570,594; U.S. 20130062124; 20120138311; 20100200243; 20090071642; 20040045724. Also of interest is J. N. McCoy Timer Control of Beam Pump Run Time Reduces Operating Expense presented at the 46th Annual Southwestern Petroleum Short Course, Lubbock, Tex. April 21-22, 1999.
Those skilled in the art will better understand the methods of the present invention from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims.
The method allows a pressure application in a string with external packers without having the packer setting apparatus exposed to tubing pressure so that at a later time and at a lower pressure than the pressure test pressure, the external packers can be set with annulus pressure opened to a piston that references a low pressure chamber. The packers can be set in any desired order. Thereafter, a port sub can be triggered to open to allow the fracking to start. Fracking each interval beyond the first in an uphole direction can be accomplished with pumping ever increasing balls to seats associated with sliding sleeves to open the sleeves in order. In cemented completions, after a pressure test, a ported sub can open on a timer or other signal to allow pumping a combination of a bridge plug and a perforating gun to the desired location.
In
The method described above addresses two potential problems when the string requires a pressure test. First, the packers are not set first before the pressure test on the string. Instead, the pressure test is run with the packers unset and their setting mechanism shielded from string test pressures or annulus pressure. Furthermore, with the packers unset the risk of creating fractures at set packer locations is removed as can happen when the higher test pressure for the string is allowed to act on the setting pistons of the already set packers to further set them to enough of a degree where they can actually initiate or greatly extend fractures in undesirable locations. The ideal situation is that the fractures initiate between the barriers rather than at the barriers. With the packers unset during the pressure test there is no risk of initial or additional fractures forming at the packer locations. When the packers are then ready to set after the pressure test, they can be set with tubing pressure that is at far lower pressures than the tubing test pressures previously used during the pressure test. If annulus pressure is to be used to set the packers then the same result obtains as the setting pressure in the annulus when the setting mechanism of the packers is exposed to such pressures is far lower than the tubing pressure during the pressure test. The setting ports are selectively made accessible to tubing or annulus pressure with timer or signal triggered valves as described above so that the packers can be set in any desired order. With the packers set another port is opened either by timer or signal to expose the lowest interval for fracking. This initial fracking of the lowermost zone allows there to be created a flow path that allows pumping of each of the progressively increasing in diameter subsequent balls to be pumped into a horizontal borehole to be quickly landed on a respective ball seat so that the intervals can be sequentially fractured in a bottom up order. This valve that operates on a timer or through a transmitted signal solves the problem of having ports closed during the pressure test and avoiding to run the pressure even higher than the pressure test pressure to get the ports to open after the pressure test ends. Instead, the circulation sub is triggered to open with time or with a transmitted or other signal so that the initial opening solves the problem of how to pump the sequential array of balls to a horizontal formation for the fracking of the zone from bottom up where there is also a need for a pressure integrity test before the fracking starts. Overpressures of the string as would occur with a pressure actuated circulation sub that had to open only after a pressure test of the string are avoided.
The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below:
