Downhole oil, gas, water and sand separation method and separator

Patent metadata

Field	Value
Publication number	US-11180980-B2
Application number	US-201816482842-A
Country	US
Kind code	B2
Filing date	Jan 12, 2018
Priority date	Feb 3, 2017
Publication date	Nov 23, 2021
Grant date	Nov 23, 2021

Abstract

A downhole oil, gas, water and sand separation method and separator ( 10 ). The downhole oil, gas, water and sand separation method comprises: step 1 : dividing an oil jacket annulus into a plurality of spaces in an outflow direction of produced liquid, wherein each space is provided with an accommodating cavity ( 21 ) communicated with the oil jacket annulus; step 2 : arranging a plurality of liquid inlet hole groups ( 11 ) in a liquid outlet pipeline ( 1 ) of the produced liquid in the outflow direction of the produced liquid, wherein each of the liquid inlet hole groups ( 11 ) is communicated with one of the accommodating cavities ( 21 ); and step 3 : separating oil, gas and water after the crude oil in the oil jacket annulus flows into each of the accommodating cavities ( 21 ), wherein separated oil drops or bubbles flow back to the oil jacket annulus from the accommodating cavities ( 21 ), and separated produced liquid simultaneously flows into the liquid outlet pipeline ( 1 ) through the plurality of liquid inlet hole groups ( 11 ). The downhole oil, gas, water and sand separation method and separator can realize a rapid downhole oil-water or gas-water separation in the high water-content crude oil.

First claim

The invention claimed is:

1. A downhole oil, gas, water and sand separation method, comprising:
(Step 1 :) dividing an oil jacket annulus into a plurality of spaces in an outflow direction of a produced liquid, wherein each of the plurality of spaces are provided with an accommodating cavity communicated with the oil jacket annulus, so that crude oil in the oil jacket annulus is divided into a plurality of parts which flow into a plurality of accommodating cavities, respectively, a descending velocity of liquid in crude oil in each of the accommodating cavities is decreased relative to a descending velocity of liquid in the crude oil in the oil jacket annulus, and an ascending velocity of oil drops or bubbles in the crude oil in each of the accommodating cavities is increased relative to an ascending velocity of oil drops or bubbles in the crude oil in the oil jacket annulus;
(Step 2 :) arranging a plurality of liquid inlet hole groups in a liquid outlet pipeline of the produced liquid in the outflow direction of the produced liquid, wherein each of the plurality of liquid inlet hole groups are communicated with one of the accommodating cavities; and
(Step 3 :) separating oil, gas and water after the crude oil in the oil jacket annulus flows into each of the accommodating cavities, wherein separated oil drops or bubbles flow back to the oil jacket annulus from the accommodating cavities, and separated produced liquid simultaneously flows into the liquid outlet pipeline through the plurality of liquid inlet hole groups,
wherein step 3 comprises:
determining pressure differences in the oil jacket annulus and the liquid outlet pipeline according to liquid production capacities of different oil wells, areas of different oil jacket annuluses, and an area of the liquid outlet pipeline; and
adjusting open areas of the liquid inlet hole groups at different positions in the liquid outlet pipeline according to the pressure differences, so that flow rates of the produced liquid simultaneously flowing into the liquid outlet pipeline through each of the liquid inlet hole groups are equal.

2. The downhole oil, gas, water and sand separation method according to claim 1 , wherein a number N of the accommodating cavities is calculated according to the following formula:

N
=

Q
⁢

T
t

8
⁢
6
⁢
4
⁢
0
⁢
0
⁢
V

wherein:
Q is a liquid production capacity of an oil well;
T t is expected residence time of the crude oil in the accommodating cavity; and
V is a volume of the accommodating cavity.

3. The downhole oil, gas, water and sand separation method according to claim 2 , wherein the expected residence time T t of the crude oil in the accommodating cavity is 25 s to 150 s.

4. The downhole oil, gas, water and sand separation method according to claim 2 , wherein the volume V of the accommodating cavity is 50 ml to 250 ml.

5. The downhole oil, gas, water and sand separation method according to claim 1 , wherein in step 2 , each of the plurality of liquid inlet hole groups comprises a plurality of liquid inlet holes spaced apart in a circumferential direction of the liquid outlet pipeline, and a diameter d of the liquid inlet hole is calculated according to the following formula:

d
=

2
⁢
0
⁢
ρ
⁢

q
2

Δ
⁢
p
⁢

π
2

4

wherein:
q is a flow rate of the produced liquid flowing through the liquid inlet hole;
p is a density of the produced liquid; and
Δp is a pressure difference between an interior and an exterior of the liquid outlet pipeline.

6. The downhole oil, gas, water and sand separation method according to claim 5 , wherein the pressure difference Δp between the interior and the exterior of the liquid outlet pipeline is calculated according to the following formula:
Δp=1.25ρv 2

wherein v is a flow velocity of the produced liquid passing through the liquid inlet hole.

7. The downhole oil, gas, water and sand separation method according to claim 5 , wherein the flow rate q of the produced liquid flowing through the liquid inlet hole is calculated according to the following formula:

q
=

Q

N
⁢
n

wherein:
Q is a liquid production capacity of an oil well;
N is a number of the accommodating cavities; and
n is a number of the liquid inlet holes in each of the liquid inlet hole groups.

8. The downhole oil, gas, water and sand separation method according to claim 1 , wherein a distance between every adjacent two of the liquid inlet hole groups is 10 mm to 55 mm.

9. The downhole oil, gas, water and sand separation method according to claim 1 , further comprising:
(Step 4 :) placing a filter material in each of the accommodating cavities, so that the oil drops in the crude oil become oil films when flowing through the filter material, and an upward pressure gradient that the oil films undergo in the filter material is larger than a downward pressure gradient that the oil films undergo, thereby promoting the oil films to slide upward in the filter material.

10. The downhole oil, gas, water and sand separation method according to claim 1 , wherein the accommodating cavity is provided with a plurality of sand outlet holes communicated with the oil jacket annulus.

11. A downhole oil, gas, water and sand separator, comprising:
a liquid outlet pipeline provided with a plurality of liquid inlet hole groups spaced apart in an axial direction thereof; and
a plurality of settling cups connected to each other and disposed around the liquid outlet pipeline, each having an accommodating cavity communicated with each of the liquid inlet hole groups, and having a liquid inlet and a plurality of sand outlet holes;
wherein the settling cup comprises:
a cup body having a peripheral wall and a bottom wall, wherein the bottom wall has an inner annular side and an outer annular side, a lower end of the peripheral wall is connected to the outer annular side of the bottom wall, a level of the outer annular side is higher than a level of the inner annular side, and the accommodating cavity is formed between the cup body and the liquid outlet pipeline; and
a cup base having an upper end connected to the inner annular side of the bottom wall, and disposed around the liquid outlet pipelin

Assignees

• Petrochina Co Ltd
• Daqing Oilfield Co Ltd

Inventors

• Wang Yan
• Wang Demin
• Zhong Rong
• Liu Quan
• Liu Jintang

Classifications

• E21B43/38 Primary

  in the well · CPC title

• E21B43/35

  specially adapted for separating solids (down-hole drilling fluid separation systems E21B21/002; separating solids from drilling fluids E21B21/065) · CPC title

• E21B43/121

  Lifting well fluids (monitoring of down-hole pump systems E21B47/008) · CPC title

• E21B33/126

  with fluid-pressure-operated elastic cup or skirt (E21B33/122, E21B33/124 take precedence) · CPC title

• E21B43/08

  Screens or liners {(expandable screens or liners E21B43/108)} · CPC title