Methods and devices for casing and cementing wellbores

A pumpable casing plug for use in a wellbore with well fluids, the casing plug comprising:

• a housing comprising a body section, a first end section, and a second end section;
• wherein the first end section of the housing is the uphole end and the second end section of the housing is the downhole end;
• wherein the housing is configured to be pumped through the wellbore in the well fluids;
• an insert defining a flow path configured, in response to fluid flow therethrough, to generate variable flow resistance to generate cyclic hydraulic loading in the well, thereby causing repeated extension and contraction of the casing string sufficient to reduce the drag force on the casing string thereby facilitating advancement of the casing string down the wellbore, wherein the insert is sized to be received in the body section of the housing;
• wherein the housing and the flow path in the insert together form a throughbore so that well fluids can be pumped through the casing plug;
• a tubular nose-cone connected to the second end section, the nose cone being wiper-free;
• and
• at least a first wiper supported on the first end section of the housing;
• wherein the body section of the housing is free of wipers.

A pumpable casing plug for use in a wellbore with well fluids, the casing plug comprising:

• a housing comprising a body section, a first end section, and a second end section;
• wherein the first end section of the housing is the uphole end;
• wherein the housing is configured to be pumped through the wellbore in the well fluids;
• an insert defining a flow path configured, in response to fluid flow therethrough, to generate variable flow resistance to generate cyclic hydraulic loading in the well, thereby causing repeated extension and contraction of the casing string sufficient to reduce the drag force on the casing string thereby facilitating advancement of the casing string down the wellbore, wherein the insert is sized to be received in the body section of the housing;
• wherein the flow path comprises:
• an inlet and an outlet;
• a jet chamber;
• a nozzle to direct fluid from the inlet into the jet chamber;
• first and second input channels diverging from the jet chamber;
• at least one vortex chamber continuous with the outlet and having first and second inlet openings;
• wherein the first input channel connects to the first inlet opening and the second input channel connects to the second inlet opening;
• wherein the first input channel and the first inlet opening in the at least one vortex chamber are configured to direct fluid flow into the vortex chamber along a tangential path to generate a primary vortex and wherein the second input channel and the second inlet opening of the vortex chamber are configured to direct fluid flow along a radial path into the vortex chamber to produce a secondary vortex that is opposite in direction and weaker in strength relative to the primary vortex;
• a feedback-operated switch to direct fluid from the inlet alternately to the first and second input channels;
• and
• a feedback control circuit configured to receive fluid alternately from primary and secondary vortices in the vortex chamber and in response thereto to operate the switch;
• wherein the housing and the flow path in the insert together form a throughbore so that well fluids can be pumped through the casing plug;
• and
• at least a first wiper supported on the first end section of the housing;
• wherein the body section of the housing is free of wipers.