1. HYDROSTATIC DEVICE FOR
KRS Oil Gas
HYDROSTATIC DEVICE FOR
BOTTOM-HOLE CLEANING
patented

2. Performance indicators comparison table for cleaning of well bottom-hole sand plug and sediments using traditional methods and hydrostatic cleaning device
(highlighted boxes by green color means advantages of using HDBHC device) №
Indicators
Traditional method
Using
HDBHC
device 1
The cost of Round trip operations of tubing for cleaning of bottom-hole of well
same 2
Average number of tubing during tripping 3
The cost of repairing of well 4
Standard time for round trip operations of tubing 5
The cost of cleaning of well bottom-hole
Yes No 6
Killing a well 7
Consumption of process liquid, m³ 8
The cost of process liquid, m³ 9
Recovery of well production rate, days
7-15
Immediately 10
Increasing of well production rate 11
Interrepair time of sucker rod pumps, days
Unchanged
Increasing 12
Duration of cleaning of sand plug in the well bottom-hole (According to Russian data), hours
120 21 13
Involving of additional technological equipment 14
Possibility of whole drain of oil-saturated portion of reservoir
Yes (for one cycle) 15
Preliminary works

3. 16
Before cleaning operation it is necessary to wash and perform pressure test of the system
Yes No 17
Hydraulic calculation of cleaning 18
Environmental impact
High 19
The risk of operation process related to the use of high pressure units 20
Effiency in absorption wells
Yes (for one cycle) 21
Possibility of cleaning of plugs with big size sediments, metallic parts and slurry cake (up to 32 mm) 22
Efficiency for cleaning of floating plugs (sand) 23
Iтcreasing of reservoir recovery in producing wells
(by pulse jetting) 24
İncreasing of reservoir intake capacity of injection wells 25
Possibility of cleaning of settled proppant 26
Cleaning of gravel 27
Cleaning of remains of casing perforation 28
Cleaning of metallic parts after milling process 29
Complete cleaning of tubing walls 30
Quantity of underground well repairing
Unchanged
Decreased

5. Oil wells operation using bottom-hole and electrical submersible pumps after the advisable and necessary pulse-jet filtration and formation stimulation.
Long-term experience of the use of bottom-hole and electrical submersible pumps shows that one of the factors improving operational performance is correct cleaning and stimulation of bottom-hole formation zone. Efficiency of the field development, flow-rates of producing wells, share of formation energy used for the fluid lifting at the well depend on the bottom-hole zone condition.
It is very important that an energy spent on the overcoming of filtration resistance (flow coefficient) in the bottom-hole zone is small enough when drawing off liquid.
Long-term development of formation and various engineering processes result in changes in distribution of internal stresses in the rock surrounding bottom-hole.
To reduce filtration resistance it is necessary to carry out pulse-jet filtration and pulse-jet stimulation of the bottom-hole zone, to increase permeability, improve communication with the hole, extension of the system of fractures or channels to facilitate inflow and reduce energy losses in this restricted formation zone.
To this end, it is recommended to use hydrostatic pulse-jet device that ensures pulse-jet cleaning and stimulation of formation.
In practice it is clear that after pulling out of hole bottom-hole pump and submersible electric pump for the overhaul or replacement, without any engineering procedures, replacement bottom-hole pumps are run into the hole and used

6. PROVISIONAL SEQUENCE OF OPERATIONS
In proposed method, after the bottom-hole or submersible electric pump has been pulled out of hole, special hydrostatic pulse-jet device is run into the hole. This device, which does not require any additional equipment, is run into the hole and activated using hoisting device at the wellhead. Device within the hole operates by up-down movement.
Use of device intended for the pulse-jet cleaning and stimulation of formation has the following advantages:
device is simple and does not require any additional equipment (work is done with the use of hoisting device available at the wellhead);
after the pulse-jet cleaning and stimulation of formation production of oil is immediately restored;
mechanical stability of the bottom-hole formation zone is not violated, caving is prevented;
efficient hydrodynamic communication between the bottom-hole and oil-filled formation;
possibility of drainage of the whole oil-filled layer.
PROVISIONAL SEQUENCE OF OPERATIONS
Scheme of assembling:
Cutting mill is run into the hole, back pressure valve and container (Tubing 73 or 89 mm) with the intake valve thereon are screwed on.
Container shall be chosen based on the following parameters: static level of fluid and volume of withdrawn soil.
Soil suction is carried out using hydrostatic principle. With the higher static level of fluid, more soil is withdrawn.
Dimensions of container Tubing 73 or 89 mm
Size of the hydrostatic device for bottom-hole cleaning Ø89, Ø95, Ø105 mm
Minimum bore diameter Ø32 mm

7. Draining (overflow) valve
Suction chamber
Back-pressure valve
Mechanical cutting mill

8. Based on agreement No 885-201 dated 29. 05
Based on agreement No dated , during the period of June, 2015 works on cleaning bottom-holes in 4 wells were carried out using hydrostatic sand-cleaning device. In the beginning of all tests height of sand plug was measured using special equipment A3-8. Static level in all wells was up to the wellhead due to well killing prior to workover.
Well № 463 ГУ-121 ЦНДГ-7 NGDU-4 NN
Parameters
Values 1
Day of placing on production 2
Technological regime
50/6-85 3
Well output prior to bottom-hole cleaning at normal operation
20/3-84 4
Well output after the bottom-hole cleaning
50/3-84 5
Perforation interval m 6
Artificial bottom-hole
1355 m 7
Initial strike of bottom-hole
1324 m 8
Diameter of production string
139.7 mm 9
Strike of bottom-hole after the work
1355 m
(actually measured 1364 m) 10
Interval of bottom-hole zone cleaned off sand plug
40 m 11
Total time of well workover
12.00 hrs
18.00 hrs (54 hrs) 12
Duration of works on bottom-hole zone cleaning
20 hrs
After POOH (lifting) of subsurface equipment bottom-hole was registered at 1324 m. When working with the hydrostatic device for bottom-hole cleaning with diameter 89 mm, 136 tubing joints were run into the hole, including 4 tubing joints with the reciprocation and pipe addition. After POOH (lifting) of subsurface equipment bottom-hole with tubing, 20 tubing joints contained thick liquid, and 20 joints were completely plugged with mechanical admixtures and sand. Well bottom-hole was measured as 1355 m (actually m). As a result, 40 m of well bottom-hole was cleaned of sand plug and mechanical admixtures. Perforation interval was completely exposed.

9. 2. Well № 4781 ГУ-45 ЦНДГ-3 NGDU-2 NN
Parameters
Values 1
Day of placing on production 2
Technological regime
40/10-70 3
Well output prior to bottom-hole cleaning at normal operation
47/ 4
Well output after the bottom-hole cleaning
70/ 5
Perforation interval m 6
Artificial bottom-hole
1722 m 7
Initial strike of bottom-hole
1704 m 8
Diameter of production string
168 mm 9
Strike of bottom-hole after the work
1722 m
(actually measured 1742 m) 10
Interval of bottom-hole zone cleaned off sand plug
38 m 11
Total time of well workover
17.00 hrs
09.00 hrs (64 hrs) 12
Duration of works on bottom-hole zone cleaning
28 hrs
After POOH (lifting) of subsurface equipment bottom-hole was registered at 1704 m. When working with the hydrostatic device for bottom-hole cleaning with diameter 89 mm, 172 tubing joints were run into the hole, including 4 tubing joints with the reciprocation and pipe addition. After POOH (lifting) of subsurface equipment with tubing, after the 80-th joint, tubing joints contained liquid, and last 8 joints were completely plugged with mechanical admixtures and sand. Well bottom-hole was measured as 1722 m (actually m). As a result, 38 m of well bottom-hole was cleaned of sand plug and mechanical admixtures. Perforation interval was completely exposed.

10. 3. Well № 3917 ГУ-5 ЦНДГ-3 NGDU-2 NN
Parameters
Values 1
Day of placing on production 2
Technological regime
90/4-95 3
Well output prior to bottom-hole cleaning at normal operation
95/ 4
Well output after the bottom-hole cleaning
100/ 5
Perforation interval m 6
Artificial bottom-hole
1257 m 7
Initial strike of bottom-hole
1085 m 8
Diameter of production string
168 mm 9
Strike of bottom-hole after the work
1225 m 10
Interval of bottom-hole zone cleaned off sand plug
140m 11
Total time of well workover
16.00 hrs
06.00 hrs (110 hrs) 12
Duration of works on bottom-hole zone cleaning
Twice hrs
After POOH (lifting) of subsurface equipment bottom-hole was registered at 1085 m. When working with the hydrostatic device for bottom-hole cleaning with diameter 95 mm, 110 tubing joints were run into the hole, including 1 tubing joint with the reciprocation and pipe addition. After (lifting) hydrostatic device for bottom-hole cleaning with tubing, 17 tubing joints contained liquid, and last 6 joints were completely plugged with mechanical admixtures and sand. Well bottom-hole was measured as 1110 m. It was decided to RIH hydrostatic device for bottom-hole cleaning again with diameter 89 mm. Hydrostatic device for bottom-hole cleaning 89-mm was run into the hole with 127 tubing joints, including 5 tubing joints with the reciprocation and pipe addition. 30 tubing joints were pulled with thick liquid and the last 4 were completely plugged with mechanical admixtures and sand. Well bottom-hole was measured as 1225 m. As a result, 140 m of well bottom-hole was cleaned of sand plug and mechanical admixtures. Perforation interval was completely exposed.

11. 4 Well № 3595 ГУ-52 ЦНДГ-9 NGDU-2 NN
Parameters
Values 1
Day of placing on production 2
Technological regime
50/3-92 3
Well output prior to bottom-hole cleaning at normal operation
57/ 4
Well output after the bottom-hole cleaning
58/ 5
Perforation interval m 6
Artificial bottom-hole
1254 m 7
Initial strike of bottom-hole
1190 m 8
Diameter of production string
168 mm 9
Strike of bottom-hole after the work
1204 m 10
Interval of bottom-hole zone cleaned off sand plug
14 m 11
Total time of well workover
09.00 hrs
13.00 hrs (76 hrs) 12
Duration of works on bottom-hole zone cleaning
Twice hrs
After POOH (lifting) of subsurface equipment bottom-hole was registered at 1190 m. When working with the with diameter 89 mm, 119 tubing joints were run into the hole, including 1 tubing joint with the reciprocation and pipe addition. After POOH (lifting) hydrostatic device for bottom-hole cleaning with tubing, tubing joints were filled with liquid, and last 4.5 joints were completely plugged with proppant. Well bottom-hole was measured as 1204 m.

12. After the analysis of completed works conclusions of commission were the following:
Using hydrostatic device for bottom-hole cleaning it is possible to remove sand plug from production well completely within one-two round trips;
Rotation of the end piece at the expense of own weight of tubing string allows hydrostatic device for bottom-hole cleaning loosening relatively compact rock at well bottom, and collect same into vacuum pipes;
RIH and POOH (lifting) of hydrostatic device for bottom-hole cleaning is carried out using special equipment and tools, which are currently employed in well workover operations;
When working with hydrostatic device for bottom-hole cleaning, tension force acting on pipes' threads is lower;
Neither special tools, no fluids are required for the flushing of well bottom-hole zone;
In line with the environmental requirements, it is mandatory to have special containers at the wellhead, to collect recovered mechanical admixtures and sand;
Currently well-workover operation teams spend 7 to 20 days on bottom-hole zone cleaning off sand plugs and mechanical admixtures, whist with hydrostatic device for bottom-hole cleaning this job is completed in average within 23 hrs, i.e. 2 (two) shifts.
Commission's view is that use of hydrostatic device for bottom-hole cleaning at "Ozenmunaigas" JSC will be viable and effective in wells with sand plugs, which block perforation intervals in production wells.
Videos of implementation of hydrostatic device for bottom-hole cleaning in Azerbaijan, Kazakhstan and Russia