Quartz School For Well Site Supervisors

Quartz School Well Site 3. Solidfor Deposits CleanSupervisors Up Module – 13 Work Over Operations

Section – 3 Solid Deposits Clean Up

Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up C. Alvarez

1/34

3. Solid Deposits Clean Up • Contents:

1.

Introduction

2.

Wash down of solid deposits

3.

Mechanical clean up of sand and soft solid deposits

4.

Removal of paraffinic wax deposits

5.

Chemical removal of asphaltic deposits and scales

6.

Prevention of chemical deposits

7.

Corrosion of equipment and its control

Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up C. Alvarez

2/34

3. Solid Deposits Clean Up 1.

Introduction

Origin of solids deposits and scaling: •Solids that are carried suspended in the reservoir fluids are settle down and build up in the well bore or at surface, inside the treating equipment, storage tanks or flow lines, when the flowing, concentration and / or physical conditions are varied. •Inside the well and surface installations due to changes in flow regime conditions, or variations in the physical & chemical properties of the fluids in the formation, in the well bore or at surface Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up C. Alvarez

3/34

3. Solid Deposits Clean Up 1.

Introduction

Example of Chemical deposit accumulation also called “Scaling”

Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up C. Alvarez

4/34

3. Solid Deposits Clean Up 1.

Introduction

Treating Solids Deposits: •

Prevention: keeping physical chemical properties appropriate to keep salts and other solids dissolved in the fluids.

•

Solids retention: Apply techniques and procedures to keep sand and solids in the reservoir by installing mechanical barriers and retention devices

•

Handling solids deposits: Develop programs for periodic clean up of solids deposits and accumulations in the well bore as well as for the maintenance or replacement of equipment and installations affected by the sand & solids deposits Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

5/34

3. Solid Deposits Clean Up 1.

Introduction

Consequences of Solids Build Up: •

Fluid production or injection blocked

•

Plugging of surface and down hole equipment

•

Damage of equipment due to erosive flow

•

Stuck of down hole tools and accessories by scale deposits and solids compacted

•

Progressive corrosion of all metallic components installed for production or fluid injection

•

Blockage of lines and equipment by paraffinic wax and asphalten

•

Enlarging of hole diameter with caverns and subsequent wellbore and casing collapses Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

6/34

3. Solid Deposits Clean Up 2.

Wash Down of Solid Deposits

Sand and soft solids build up – Characteristics: •

High rate of sand production quick solids build up

•

Progressive or rapid lost in well productivity

•

Conditions known and tolerated by the operator

•

Most common in flowing wells and sucker rod production

•

Frequent failures of down hole equipment

•

Blockage and severe damage of surface installations

•

Environment concerns and high costs for handling, treating and disposal of oil impregnated solids Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

7/34

3. Solid Deposits Clean Up 2.

Wash Down of Solid Deposits

Equipment and Materials Requirements: • • • • • • •

Light service work over unit Circulating system (simplified) Rotating System (optional) Control and Work Over fluids BOP and WC Equipment (optional) Shale Shaker or Simple Screen for solids separation and discarding at surface Special equipment and procedures for handling treating, transporting and disposal of contaminated solids discarded on location Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

8/34

3. Solid Deposits Clean Up 2.

Wash Down of Solid Deposits

General Procedure: 1. Rig up and test the light service WO unit 2. Control well flowing (if required) 3. Dismantle well head and surface installations 4. Nipple up and test BOP stack (if required) 5. Pull out of hole drill string and accessories 6. Inspect components pulled out and order the required repairing or replacements Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up C. Alvarez

9/34

3. Solid Deposits Clean Up 2.

Wash Down of Solid Deposits

General Procedure – continued… 7.

Run work string with accessories for cleaning deposits (coupling with like tooth profile, wash over shoe, mill, drill bit, etc.)

8.

It is a common practice to use same tubing string pulled out of hole as a work string for wash over and light work over operations

9.

Tag bottom and measure or confirm the reported sand or solids build up height in the well Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

10/34

3. Solid Deposits Clean Up 2.

Wash Down of Solid Deposits

General Procedure – continued… 10. Start washing down on the solid deposit circulating work fluid through the tubing and take the returns over the shale shaker of screen installed for solids separation at surface 11. Rotate and slack off on the wash coupling or shoe if the solid deposit is hard or compacted 12. Continue washing down in a controlled manner to avoid work string stuck. Circulate clean before making a new connection and when finish the washing down 13. Pull the work string out of hole Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up C. Alvarez

11/34

3. Solid Deposits Clean Up 2.

Wash Down of Solid Deposits General Procedure – continued… 14. Run the production / injection string with all down hole equipment and accessories according to the well completion design 15. Nipple down the BOP stack, Install and test Christmas Tree, lines and well head accessories 16. Left well active or hand it over to the production department Additional Considerations: 1. Used crude oil or clean fluid as work fluid 2. Add viscosifiers to improve solids carrying capacity 3. Install steel screens and sand trap to separate and collect solids at surface Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

12/34

3. Solid Deposits Clean Up 3.

Mechanic Removal of Sand and Soft Deposits

Conditions for its application: 1. Low to moderated sand / sediments production 2. Lack of well service rig with circulating system 3. Soft / non compact deposits 4. There is no sand control devices installed in the hole 5. There is a program established for periodic clean up 6. More common in low pressure and sucker rod pumping producer wells 7. The clean up is carried out through tubing 8. In sucker rod pumping the rod string is PPOH first Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up C. Alvarez

13/34

3. Solid Deposits Clean Up 3.

Mechanic Removal of Sand and Soft Deposits Equipment and Tools: • Light, self propelled, trailed or skid mounted well service unit • Sand line drum with enough length of wire rope to reach well TD. • Power system transmission, driller’s console and basic rig instrumentation • Sand line depth meter and swivel rope socket

Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up C. Alvarez

14/34

3. Solid Deposits Clean Up 3.

Mechanic Removal of Sand and Soft Deposits

Equipment and Tools – continued… 1.

2. 3. 4. 5.

Sand pump consisting in one tubular barrel to be run in the hole with sinker bars connected to the swivel rope socket of the sand line Mechanical suction created by internal sliding sleeve spring loaded Sand and solids deposit container located at surface Handling tools for pulling out sucker rods, pumps or traveling piston connected to the standing valve Transport, treatment and final disposal of oil wet solids Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

15/34

3. Solid Deposits Clean Up 3.

Mechanic Removal of Sand and Soft Deposits

General Procedure: 1.

Stop the pumping unit and dismantle surface lines and connections (if applicable)

2.

Rig up and test the described light well servicing unit and accessories

3.

POOH the sucker rod string (if applicable). Assure that the standing valve was pulled out with the piston if installed a pump tubing type.

4.

Connect the sand suction pump to the swivel rope socket of the sand line Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

16/34

3. Solid Deposits Clean Up 3.

Mechanic Removal of Sand and Soft Deposits

General Procedure – continued… 5.

Reset the depth meter installed on the sand line when the pump is at rotary table or well head level

6.

Run the sand pump at a moderated velocity taking care of not hitting the fluid level inside the tubing or the solid pile top at high speed. Severe injures or death have occurred

7.

Tag bottom, and mark the wire rope at surface. Operate the pump by hitting at a moderate velocity the top of solids and weight a few seconds to fill the barrel with sand

8.

Pull the pump out of the well and dump the barrel content at the surface

9.

Repeat steps 6 to 9 until almost all solid deposit have been cleaned up Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

17/34

3. Solid Deposits Clean Up 4. Removal of Paraffin Wax Deposits Conditions for Occurrence of Paraffin Wax Deposits: 1.

The dissolved paraffin present in light crudes is precipitated when the conditions of temperature and pressure are altered

2.

When temperature is reduced below the “cloud point” along the flow path of formations fluids from the reservoir to surface

3.

When flow velocity inside the well bore is reduced or due to a reduction in the bottom hole pressure

4.

In reason of a low gas / oil ratio

5.

In producing wells having a tubing ID less than 2.5” Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

18/34

3. Solid Deposits Clean Up 4. Removal of Paraffin Wax Deposits Mechanical Retrieval: Retrieval of wax deposited inside the tubing with the cutting action of a hole cylinder scraper run with a sucker rod string. The wax is forced inside a tubular barrel connected above the scraper

Required Equipment: 1.

Hollow cylinder scraper with belled cutting structure in front and tubular barrel above it

2.

Connector to attach the barrel to the rod string or wire rope (sand line)

3.

Secondary drum of a WO unit (sand line drum) or swabbing unit trailer or skid mounted Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

19/34

3. Solid Deposits Clean Up 4. Removal of Paraffin Wax Deposits Mechanic Removal. Required Equipment – continued… 1.

Conventional light well servicing unit

2.

Rod sucker handling tools

3.

Tank or portable metallic box for depositing the recovered paraffin wax

4.

Steam water heater for the clean up of down hole tools and production string components Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

20/34

3. Solid Deposits Clean Up 4. Removal of Paraffin Wax Deposits Mechanical Removal: Operational Procedure: 1.

Apply well control procedure either circulating with a kill fluid or with bull heading (if required)

2.

Disconnect surface lines and lay down the Christmas tree

3.

Nipple up and test BOP stack if required

4.

Install and test conventional well service

5.

Release sucker rod pump and pull out with the sucker rod string

Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up C. Alvarez

21/34

3. Solid Deposits Clean Up 4. Removal of Paraffin Wax Deposits Mechanical Removal: Operational Procedure – continued 6.

Connect the wax scrapper and accessories (barrel, sinker bars, hydraulic or mechanical jar) to the sand line or to the sucker rod string

7.

Run the scraper along the tubing string at a moderated speed to fill the barrel with wax

8.

Pull the barrel out of hole and recover the paraffin wax

9.

Repeat steps 7 and 8 until the wax deposit is removed from the pipe Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

22/34

3. Solid Deposits Clean Up 4. Removal of Paraffin Wax Deposits Other Wax Removal Options: Periodic change of production string blocked / obstructed with paraffin deposits 1.

Rig up a light well servicing unit with circulation system and BOPE

2.

Perform well control if required

3.

Disconnect surface lines and accessories and R/D the Christmas tree

4.

N/U and test BOP stack if required

5.

POOH and lay down all components of production string

6.

Discard those tubing joints plugged with paraffin Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

23/34

3. Solid Deposits Clean Up 4. Removal of Paraffin Wax Deposits Other Wax Removal Options – continued… Periodic change of production string blocked / obstructed with paraffin deposits 7.

Run into the well a clean production string and accessories

8.

Activate the production

9.

Send the obstructed / plugged tubing for cleaning at the shop

Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up C. Alvarez

24/34

3. Solid Deposits Clean Up 4. Removal of Paraffin Wax Deposits Other Wax Removal Options: Heating: Paraffin was is kept in solution in the produced fluids by increasing the temperature above the cloud point both inside the well, in the surface production installations and along the flow lines 1. 2. 3.

Electric heater are pre-installed in the tubing string Electric heaters or heat exchangers (steam or combustion gases) are used for heating surface installations and flow lines Injection of hot crude oil through a control line attached to the tubing string in the well Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

25/34

3. Solid Deposits Clean Up 4. Removal of Paraffin Wax Deposits Other Wax Removal Options: Paraffin Solvent Bars and Chemical Sequestrants: 1.

Paraffin solvent bars or discs are pre-installed inside a cage in the drilling string or drop from surface at periodic intervals of time to keep the wax dissolved in the crude oil

2.

Solvent solutions (aromatic hydrocarbons) and sequestrants are injected into the production string through a control line externally attached to the tubing in flowing wells, by means of programmed electrical pumps at surface Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

26/34

3. Solid Deposits Clean Up 5. Chemical Removal of Asphaltic Deposits and Scales Origin: 1.

Solids deposits product of chemical in the reservoir, down hole equipment or surface installations

2.

Precipitation of salts and other materials from fluids with high concentration of dissolved salts, oxides, carbonates, sulfates, sulfur, halides, etc.

3.

Scaling is possible in well both in natural flow or with artificial lift installations Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

27/34

3. Solid Deposits Clean Up 5. Chemical Removal of Asphaltic Deposits and Scales Equipment and Materials and Procedures: 1.

2.

3. 4.

Electric pumps programmed for injecting treating chemicals with the proper doses and at regular intervals of time Service line or control line (made of copper and ¼” of diameter), externally attached to the production tubing Cage for installing solvent bars or chemical sequestrants that keep the salts in solution Aromatic solvents for elimination of asphaltic deposits Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

28/34

3. Solid Deposits Clean Up 5. Chemical Removal of Asphaltic Deposits and Scales Equipment and Materials and Procedures: 1.

Acid mixtures injected also with the programmed pumps to the control line

2.

Iron sequestering agents (organic acids) or buffer solutions injected into the tubing to prevent the precipitation of ferric oxide scales

3.

Conventional Work Over Unit with circulating system capable of handle tubing string (optional)

4.

High pressure / High volume pumps for well stimulation (rig less well intervention) Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up

C. Alvarez

29/34

3. Solid Deposits Clean Up 5. Chemical Removal of Asphaltic Deposits and Scales Equipment Materials and Procedures: 5.Circulating from tubing to the annulus through sliding sleeve, ported nipple, or pre-installed injection valves 1.Formation face clean up (spotting solvents in front of formation to dissolve scaling and other chemical deposits after a given soak time) 2.Removal of scales by dissolving with acid mixtures placed in front of perforations and injected into the formation 6.Circulation of solvents or acid mixtures through a concentric tubing preinstalled inside the production string 7.Circulation of solvents or acid mixtures through a control line external to the tubing string Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up C. Alvarez

30/34

3. Solid Deposits Clean Up 5. Chemical Removal of Asphaltic Deposits and Scales Heaters and heat exchangers installed at the surface

Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up C. Alvarez

31/34

3. Solid Deposits Clean Up 6. Prevention of Sand Production and Chemical Deposits Reduction / Elimination of Sand and Solids Production: 1.

2. 3. 4. 5.

Cement casing or production liner and perforate selectively in the proper direction to avoid the production of sand from unconsolidated formations Design the perforations according to the mechanical properties of the reservoir rocks Regulate the bottom draw down pressure to prevent erosive flow from reservoir to the well bore Install sand retention screens in open hole completions Block sand production with in-situ consolidation or by installing special sand control devices (wire screens, pre-packed screens, external packing of slotted liners or screens, etc.

NOTE: Sand control procedures will be covered in another section Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up C. Alvarez

32/34

3. Solid Deposits Clean Up 6. Prevention of Sand Production and Chemical Deposits Paraffin Wax Deposits: 1. 2. 3. 4. 5.

Control physical chemical conditions along the system: well bore and surface installations Control fluid velocity in the well and on surface. Avoid low flow rates Use solvents and sequestering agents in contact with the produced fluids inside the tubing string Inject / circulate chemical treatment with programmed dispenser pump Heat all equipment in the hole and on surface with electric resistances or heat exchangers

Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up C. Alvarez

33/34

3. Solid Deposits Clean Up 6. Prevention of Sand Production and Chemical Deposits Chemical Deposits / “Scales”: 1. 2.

3. 4. 5.

Programmed injection of chemical treatment to keep in solution dissolved salts and heavy HC components Periodic clean up by spotting acid mixtures or solvents in front of formation face plus a given soak time to dissolve or prevent the build up of scales and deposits Injection of surfactants and emulsion breakers into the reservoir Injection / circulation of aromatic solvents to prevent the precipitation of asphaltic components Addition of sequestering agents to the produced fluid

Quartz School. Module 13: Work Over Operations / Section 3: Solid Deposits Clean Up C. Alvarez

34/34