Method of creating a zonal isolation in an underground wellbore

A method of creating a zonal isolation adjacent to a target zone in an underground wellbore, the method comprising:

• inserting a slurry injection tubing through a wellhead into the wellbore;
• arranging a particle accumulation means in an annular space surrounding the slurry injection tubing at a location between the target zone and the wellhead;
• and
• pumping a slurry comprising a carrier fluid and granular material via the slurry injection tubing into the annular space, such that at least some granular material accumulates adjacent to the particle accumulation means and the accumulated granular material forms a zonal isolation comprising packed granular material adjacent to the particle accumulation means;
• wherein the particle accumulation means comprises an expandable screen assembly which is permeable to the carrier fluid, but impermeable to at least some of the granular material;
• and the method further comprises:
• radially expanding the screen assembly within the annular space;
• and
• inducing the fluid slurry to flow in longitudinal direction through the annular space such that at least some carrier fluid is induced to flow through the expanded screen assembly and at least some granular material is induced to settle and accumulate against the expanded screen assembly, thereby forming a zonal isolation comprising a matrix of packed granular material in the annular space between the target zone and the expanded screen assembly.

A method of creating a zonal isolation adjacent to a target zone in an underground wellbore, the method comprising:

• inserting a slurry injection tubing through a wellhead into the wellbore;
• arranging a particle accumulation means in an annular space surrounding the slurry injection tubing at a location between the target zone and the wellhead;
• and
• pumping a slurry comprising a carrier fluid and granular material via the slurry injection tubing into the annular space, such that at least some granular material accumulates adjacent to the particle accumulation means and the accumulated granular material forms a zonal isolation comprising packed granular material adjacent to the particle accumulation means;
• wherein the slurry injection tubing is radially expanded after inserting a matrix of packed granular material in the annulus between the slurry injection tubing and the wellbore, thereby increasing the packing density and decreasing the permeability of the matrix of packed granular material.

A method of creating a zonal isolation adjacent to a target zone in an underground wellbore, the method comprising:

• inserting a slurry injection tubing through a wellhead into the wellbore;
• arranging a particle accumulation means in an annular space surrounding the slurry injection tubing at a location between the target zone and the wellhead;
• and
• pumping a slurry comprising a carrier fluid and granular material via the slurry injection tubing into the annular space, such that at least some granular material accumulates adjacent to the particle accumulation means and the accumulated granular material forms a zonal isolation comprising packed granular material adjacent to the particle accumulation means;
• wherein the particle accumulation means is provided by a region of the annular space, in which the fluid velocity is reduced and granular material is induced to settle by an increased cross-section of the annular space with respect to an upstream region thereof with regard to slurry flow.

A method of creating a zonal isolation adjacent to a target zone in an underground wellbore, the method comprising:

• inserting a slurry injection tubing through a wellhead into the wellbore;
• arranging a particle accumulation means in an annular space surrounding the slurry injection tubing at a location between the target zone and the wellhead;
• and
• pumping a slurry comprising a carrier fluid and granular material via the slurry injection tubing into the annular space, such that at least some granular material accumulates adjacent to the particle accumulation means and the accumulated granular material forms a zonal isolation comprising packed granular material adjacent to the particle accumulation means;
• wherein the particle accumulation means comprises a means for removing liquid from the slurry, selected from the group consisting of a fluid permeable barrier in the annular space and a fluid return conduit surrounding the slurry injection tubing;
• wherein during pumping of the slurry at least part of the carrier fluid is removed from the slurry;
• and
• wherein the particle accumulation means comprises a fluid return conduit surrounding the slurry injection tubing, which fluid return conduit has a permeable outer wall, and wherein at least some fluid is induced to flow from the annular space into the fluid return conduit.

A method of creating a zonal isolation adjacent to a target zone in an underground wellbore, the method comprising:

• inserting a slurry injection tubing through a wellhead into the wellbore;
• arranging a particle accumulation means in an annular space surrounding the slurry injection tubing at a location between the target zone and the wellhead;
• and
• pumping a slurry comprising a carrier fluid and granular material via the slurry injection tubing into the annular space, such that at least some granular material accumulates adjacent to the particle accumulation means and the accumulated granular material forms a zonal isolation comprising packed granular material adjacent to the particle accumulation means;
• wherein the particle accumulation means comprises a means for removing liquid from the slurry, selected from the group consisting of a fluid permeable barrier in the annular space and a fluid return conduit surrounding the slurry injection tubing;
• wherein during pumping of the slurry at least part of the carrier fluid is removed from the slurry;
• and
• wherein the slurry injection tubing is inwardly tapered or has a stepwise reduced inner and outer diameter in the region between the target zone and the expandable screen assembly, such that the velocity of the slurry in the annular space is reduced when the slurry flows from the target zone towards the screen assembly.

A method of creating a zonal isolation adjacent to a target zone in an underground wellbore, the method comprising:

• inserting a slurry injection tubing through a wellhead into the wellbore;
• arranging a particle accumulation means in an annular space surrounding the slurry injection tubing at a location between the target zone and the wellhead;
• and
• pumping a slurry comprising a carrier fluid and granular material via the slurry injection tubing into the annular space, such that at least some granular material accumulates adjacent to the particle accumulation means and the accumulated granular material forms a zonal isolation comprising packed granular material adjacent to the particle accumulation means;
• wherein the fluid slurry comprises a cement slurry from which the carrier fluid is removed during accumulation.

A method of creating a zonal isolation adjacent to a target zone in an underground wellbore, the method comprising:

• inserting a slurry injection tubing through a wellhead into the wellbore;
• arranging a particle accumulation means in an annular space surrounding the slurry injection tubing at a location between the target zone and the wellhead;
• and
• pumping a slurry comprising a carrier fluid and granular material via the slurry injection tubing into the annular space, such that at least some granular material accumulates adjacent to the particle accumulation means and the accumulated granular material forms a zonal isolation comprising packed granular material adjacent to the particle accumulation means;
• wherein the particle accumulation means is provided with magnets and the granular material comprises magnetisable components.

A method of creating a zonal isolation adjacent to a target zone in an underground wellbore, the method comprising:

• inserting a slurry injection tubing through a wellhead into the wellbore;
• arranging a particle accumulation means in an annular space surrounding the slurry injection tubing at a location between the target zone and the wellhead;
• and
• pumping a slurry comprising a carrier fluid and granular material via the slurry injection tubing into the annular space, such that at least some granular material accumulates adjacent to the particle accumulation means and the accumulated granular material forms a zonal isolation comprising packed granular material adjacent to the particle accumulation means;
• wherein the particle accumulation means comprises a means for removing liquid from the slurry, selected from the group consisting of a fluid permeable barrier in the annular space and a fluid return conduit surrounding the slurry injection tubing;
• wherein during pumping of the slurry at least part of the carrier fluid is removed from the slurry;
• and
• wherein the zonal isolation of accumulated granular material is configured such that it has a higher longitudinal permeability than at least a substantial part of the formation surrounding the target section of the wellbore.