Drilling assembly and method for drilling a barehole into geological formations
AssigneeShell Oil Company
InventorJohannes Van Wijk
Life of this patent
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Abstract
A drilling assembly for drilling a borehole into geological formations. The assembly comprises a drilling shaft and a pump device, both placable in the borehole. The drilling shaft comprises a drilling head, and the pump device comprises a sealing device for sealing a first borehole part below the sealing device from a second borehole part above the sealing device. The pump device is enabled to pump a fluid from the first borehole part to the second borehole part.
Claims19
A drilling assembly for drilling a borehole into geological formations, said drilling assembly comprising:
- a drilling shaft placable in the borehole, which shaft comprises a drilling head;
- a pump device placable in the borehole, wherein the pump device comprises primary sealing means for sealing a first borehole part below the primary sealing means from a second borehole part above the primary sealing means, and wherein the pump device is enabled to pump a fluid from the first borehole part to the second borehole part;
- a substantially tube shaped casing placable in the borehole, said casing comprising near one end of the casing a secondary sealing means for closing said one end of the casing whereby the first borehole part is divided into lower and upper sections, which secondary sealing means is capable of keeping the pressure in the lower section lower than the pressure in the upper section.
A drilling assembly for drilling a borehole into geological formations, said drilling assembly comprising:
- a drilling shaft placable in the borehole, which shaft comprises a drilling head;
- a pump device placable in the borehole, wherein the pump device comprises primary sealing means for sealing a first borehole part below the primary sealing means from a second borehole part above the primary sealing means, and wherein the pump device is enabled to pump a fluid from the first borehole part to the second borehole part;
- a substantially tube shaped casing placable in the borehole, said casing comprising near one end of the casing a secondary sealing means for closing said one end of the casing, wherein an opening is arranged in the casing wall to which the pump device is connectable.
A method of drilling a borehole into geological formations, the borehole comprising a secondary sealing means shutting off a bottom part of the borehole, said method comprising the following steps:
- arranging a drilling shaft in the borehole above the secondary sealing means, which shaft comprises a drilling head;
- arranging a pump device in the borehole above the secondary sealing means, wherein the pump device comprises primary sealing means for sealing a first borehole part below the primary sealing means from a second borehole part above the primary sealing means, the drilling head being located in the first borehole part;
- operating the pump device so as to reduce a hydrostatic pressure in the first borehole part;
- opening the secondary sealing means;
- driving the drill shaft to deepen the borehole below the secondary sealing means.
Dependencies are inferred from the claim text.