Intakes and gas separators for downhole pumps, and related apparatuses and methods
View Patent ↗Intake and gas separators for a downhole rotary pump define a fluid flowpath and comprise two or more intake stages arranged in parallel, and two or more of the intake stages each have one or more impellers and one or more inlet holes.
1 . A multi-stage intake of a downhole rotary pump comprising:
a housing, which defines a fluid flowpath;
two or more intake stages arranged axially relative to one another within the housing, and structured to intake fluid from a wellbore in parallel, with each of the two or more of intake stages having:
one or more impellers; and
an inlet hole that is oriented to permit fluid from the wellbore to enter into the fluid flowpath.
2 . The multi-stage intake of claim 1 comprising three or more intake stages.
3 . The multi-stage intake of claim 1 in which the inlet holes of adjacent intake stages, of the two or more intake stages are separated by at least one impeller.
4 . The multi-stage intake of claim 1 in which the housing comprises a plurality of housings, one for each intake stage, of the two or more intake stages.
5 . The multi-stage intake of claim 1 in which, one or more intake stages, of the two or more intake stages, have a ratio, of an axial length to outer diameter of an outer housing of the intake stage, of 4.0:1 or less.
6 . The multi-stage intake of claim 5 in which one or more intake stages, of the two or more intake stages, have an axial length to outer diameter ratio of 2.0:1 or less.
7 . The multi-stage intake of claim 1 in which, for one or more intake stages, of the two or more intake stages:
the intake stage comprises an outer housing and an inner housing;
an annular plenum is defined between the inner housing and outer housing;
the inlet hole comprises an inner inlet hole and an outer inlet hole;
the inner housing defines the inner inlet hole; and
the outer housing defines the outer inlet hole to permit entry of fluid into the annular plenum.
8 . The multi-stage intake of claim 7 in which the annular plenum has sufficient volume to allow residence time for gas bubbles to coalesce and rise out of the fluid by buoyancy.
9 . The multi-stage intake of claim 7 in which the outer inlet holes is axially above the inner inlet hole to allow gas bubbles to coalesce and rise out of the fluid by buoyancy.
10 . The multi-stage intake of claim 7 in which the outer inlet hole has a ratio, of a cumulative open flow area through the outer inlet hole to a flow area within the annular plenum, of greater than 1.
11 . The multi-stage intake of claim 1 in which an intake stage, of the two or more intake stages, comprises:
an intake housing defining the fluid flowpath and the inlet hole to the fluid flowpath; and
the one or more impellers being an intake impeller configured to draw fluid through the inlet hole and supply the fluid into the fluid flowpath.
12 . The multi-stage intake of claim 11 in which one or more intake stages, of the two or more intake stages, defines:
an axial flowpath for axial flow of fluid from an upstream end to a downstream end of the intake stage; and
a crossover flowpath to ingest fluid from the inlet hole and provide the fluid to the one or more impellers, which are radially inward of the crossover flowpath.
13 . The multi-stage intake of claim 12 in which one or more intake stages, of the two or more intake stages, comprise two or more impellers.
14 . The multi-stage intake of claim 13 in which, for one or more intake stages, of the two or more intake stages, the crossover flowpath comprises a gathering space chamber configured to receive fluid from the inlet hole and provide the fluid to two impellers arranged in parallel within the intake stage.
15 . The multi-stage intake of claim 14 in which, for one or more intake stages, of the two or more intake stages, a radial thickness of the one or more impellers, between an inner impeller diameter and an outer impeller diameter, is between 15 and 75% of a radial distance between an outer wall of a central rotating shaft and an inner diameter of an outer housing.
16 . The multi-stage intake of claim 1 in which one or more intake stages, of the two or more intake stages, comprise:
an outer housing with an outer inlet hole;
an inner housing radially inward of the outer housing defining the fluid flowpath;
the inner housing defining an inner inlet hole;
the space between the inner housing and outer housing defining an annular plenum; and
an impeller within the inner housing and configured with a radially outward intake impeller portion.
17 . The multi-stage intake of claim 16 in which a cross-sectional area of the outer inlet hole is sufficient to allow for gas bubbles to coalesce and rise out of the fluid by buoyancy and a volume of the annular plenum below the outer inlet hole provides a sufficient reserve volume of liquid rich fluid to avoid gas locking during slug flow events in a wellbore.
18 . The multi-stage intake of claim 16 in which the outer inlet hole is axially above the inner inlet hole, to allow gas bubbles to coalesce and rise out of the fluid by buoyancy.
19 . The multi-stage intake of claim 16 in which one or more intake stages comprise a plurality of outer inlet holes angularly spaced from one another about a circumference of the housing.
20 . The multi-stage intake stage of claim 16 in which the inner inlet hole forms an inlet conduit that is angled to direct fluid to align with a downhole direction of fluid flow within the annular plenum and promote uphole motion of gas bubbles uphole and out of the annular plenum.
21 . The multi-stage intake of claim 16 comprising three or more intake stages.
22 . The multi-stage intake of claim 16 in which one or more intake stages, of the two or more intake stages, each have a length to outer diameter ratio of 4.0:1 or less.
23 . The multi-stage intake of claim 16 in which a diffuser with vanes is disposed in proximity to the impeller providing radial support to a shaft.
24 . The multi-stage intake of claim 23 in which the diffuser:
defines a gas crossover flowpath between a gas entry point and a gas outlet;
has one or more hollow vanes within which the gas crossover flowpath is at least partially defined; and
is structured to exhaust gas from an entry point, through the gas crossover flowpath, and into the annular plenum defined between the inner housing and outer housing.
25 . The multi-stage intake of claim 16 in which, for one or more intake stages, the outer inlet hole is elongate in an axial direction.
26 . The multi-stage intake of claim 25 in which, for one or more intake stages, of the two or more intake stages, an inlet section defined by the outer inlet hole has a cumulative length between 20% and 70% of a cumulative stage axial length.
27 . The multi-stage intake of claim 25 in which, for two or more intake stages, of the two or more intake stages, an inlet section defined by the outer inlet hole has a cumulative axial length with a ratio, of the axial length of the inlet section to an outer diameter of the housing at the outer inlet hole, of greater than 4.
28 . The multi-stage intake of claim 16 in which, for one or more intake stages, of the two or more intake stages, the radially outward intake impeller portion is configured to draw fluid axially downhole, such that thereafter the fluid turns radially inward and axially uphole, mixing with the fluid from upstream stages, of the two or more intake stages, and together the mixed fluids pass though a radially inward intake impeller portion in an uphole direction.
29 . The multi-stage intake of claim 28 in which a vane helix direction of the outer intake portion of the impeller is opposite to a vane helix direction of the radially inward portion of the impeller.
30 . The multi-stage intake of claim 28 in which the inner inlet hole is oriented in a generally axial direction and the outer intake portion of the intake impeller is arranged for flow in generally in a downhole direction.
31 . The multi-stage intake of claim 30 in which the outer intake portion of the intake impeller is primarily radial and is configured to move the fluid in a downhole direction and a radially outward direction.
32 . The multi-stage intake of claim 30 in which the outer intake portion of the intake impeller is configured to direct fluid in a downhole and radial outward direction.
33 . The multi-stage intake of claim 16 in which for one or more intake stages, of the two or more intake stages:
the one or more intake stages define an axial flowpath for axial flow of fluid from an upstream intake stage to flow uphole through a radially inward portion, of the impeller, configured to pass fluid axially past the impeller; and
the radially outward intake impeller portion is configured to draw fluid through the inner inlet hole and provide the fluid to the axial flowpath.
34 . The multi-stage intake of claim 33 in which vanes of the impeller are continuous between the radially inward portion of the impeller and the outer intake portion of the impeller and there is no surface dividing the two.
35 . The multi-stage intake of claim 33 in which the inner inlet hole is configured to direct fluid in a radially inward direction into an intake impeller.
36 . The multi-stage intake of claim 35 structured to direct incoming fluid:
in a downhole direction in the annular plenum;
radially inward through the inner inlet hole; and
in an uphole direction through the radially outward intake impeller portion.
37 . The multi-stage intake of claim 36 in which a cylindrical or frusto-conical surface separates the radially inward portion of the impeller from the outer intake portion of the impeller.
38 . The multi-stage intake of claim 37 in which vane design is different on the radially inward portion of the impeller from the vane design on the outer intake portion of the impeller, such that the vane design on the outer intake portion is structured to create more pressure with a lower flow rate.
39 . A downhole pump comprising a plurality of the multi-stage intakes of claim 1 .
40 . The downhole pump of claim 39 wherein:
an assembly of the intake stages, of the two or more intake stages, has a ratio, of a cumulative open flow area through an outer inlet hole of all intake stages in the assembly, to a flow area inside an inner housing, of greater than 4;
a reserve-fluid volume that is created in use by a length of annular plenum defined between a bottom of the outer inlet hole and a top of an inner inlet hole;
three or more intake stages, of the two or more intake stages, are arranged in parallel; and
such that efficient gravity-based separation of gas is allowed in use while also providing a reserve volume of fluid to improve tolerance to transient gas slug flow in a wellbore, and a high total intake flow rate to a downstream gas separator or pump stages.
41 . A downhole rotary pump comprising the multi-stage intake of claim 1 .
42 . A method comprising operating the downhole rotary pump of claim 41 by driving each intake stage, of the two or more intake stages, to intake fluid in parallel into the fluid flowpath.
43 . A method comprising operating the downhole rotary pump of claim 41 with:
the impeller of one or more intake stages, of the two or more intake stages, autonomously regulates the inflow rate from each intake stage; and
intake stages with higher density fluid at the impeller provide a higher volumetric flow rate and contribution to the total inflow than intake stages with a lower density fluid.
44 . A method comprising operating the downhole rotary pump of claim 41 wherein the impeller of each intake stage, of the two or more intake stages, creates sufficient pressure to overcome friction pressure losses within the fluid flowpath allowing approximately equal contribution from all intake stages regardless of their position toward the bottom or the top of the downhole rotary pump.