WO-2026096572-A1 - ANTI-SYPHON DEVICE AND CHEMICAL INJECTION MANDREL

Abstract

An anti-syphon device and chemical injection mandrel thereof prevents syphoning even as formation pressures decline. While conventional chemical injection mandrels rely solely on production tubing pressure to prevent syphoning, the anti-syphon device includes a sealing chamber for stem engagement, a power section chamber for a power spring, and an isolation chamber that transmits annular pressure, without fluid communication, to the stem to assist the power section. As formation pressures decline, conventional chemical injection mandrels fail when the hydrostatic head pressure exceeds the tubing pressure, resulting in syphoning. The anti-syphon device counters this by using annular pressure communicated via the isolation chamber without fluid communication to provide an assist that drives the axial translation of the stem upward onto its seat, preventing syphoning. Advantageously, this robust mechanism prevents syphoning even as formation pressures decline and increases the operational reliability and longevity of the anti-syphon device and chemical injection mandrel thereof.

Inventors

• PORTTIN, NOLAN
• BROOK, Curtis
• Mabry, Wayne
• MAILAND, JASON
• HENSCHEL, ROBERT
• PETTY, CHRIS
• NIENHUIS, Case
• KOVAR, ROBERT
• HILL, THOMAS
• LINDSTRAND, TYLER

Assignees

• TEJAS RESEARCH & ENGINEERING, LLC

Dates

Publication Date

20260507

Application Date

20251029

Priority Date

20241029

Claims (20)

1. 1. An anti-syphon device for a chemical injection mandrel comprising: a sealing chamber comprising: an inlet port disposed on a top distal end of the sealing chamber that fluidly connects the sealing chamber to a connection port, a communication port disposed on a side of the sealing chamber that fluidly connects the sealing chamber to a double check valve of the mandrel via a communication path, and a first translation port disposed on a bottom distal end of the sealing chamber that permits axial translation of an engagement portion of a stem; a sealing section disposed below the sealing chamber comprising: a plurality of seals disposed about the sealing section that permits axial translation of the engagement portion of the stem, and a second translation port disposed on a bottom distal end of the sealing section that permits axial translation of the engagement portion of the stem; a power section chamber disposed below the sealing section comprising: a fluidly isolated power spring disposed about a spring interface portion of the stem, and a third translation port disposed on a bottom distal end of the power section that permits axial translation of the spring interface portion of the stem; and an isolation chamber disposed below the power section chamber comprising a membrane in fluid communication with an annular fluids port that is fluidly connected to an annulus surrounding the mandrel, wherein the membrane communicates annular pressure to a bottom distal end of the stem, without fluid communication, to the power section.
2. 2. The anti-syphon device of claim 1 , wherein the sealing chamber is fluidly isolated from the sealing section.
3. 3. The anti-syphon device of claim 1, wherein the sealing section is fluidly isolated from the power section chamber.
4. 4. The anti-syphon device of claim 1, wherein the power section chamber is fluidly isolated from the isolation chamber.
5. 5. The anti-syphon device of claim 1 , wherein when the total injection pressure consists only of hydrostatic head pressure and a tubing pressure is not sufficient to cause the double check valves of the mandrel to close, communicated annular pressure provides an assist to the power spring of the power section chamber to overcome the hydrostatic head pressure and cause the stem to axially translate upward until a stem tip is on seat, thereby preventing a syphoning of chemicals.
6. 6. The anti-syphon device of claim 1, wherein under normal operating conditions when the total injection pressure exceeds a tubing pressure, a positive pressure differential causes the stem to axially translate downward such that a stem tip is moved off seat, thereby permitting chemicals to flow through the sealing chamber to the double check valves and into an interior of a central lumen of the chemical injection mandrel.
7. 7. The anti-syphon device of claim 1, wherein under normal operating conditions when the total injection pressure is less than a tubing pressure, a negative pressure differential causes the double check valves of the chemical injection mandrel to close and causes the stem to axially translate upward until a stem tip is on seat, thereby preventing chemical injection.
8. 8. The anti-syphon device of claim 1, wherein the engagement portion of the stem is at least partially disposed within the sealing chamber and the sealing section and the spring interface portion of the stem is at least partially disposed within the power section chamber and the third translation port.
9. 9. The anti-syphon device of claim 1 , wherein the engagement portion of the stem has a larger diameter than the spring interface portion of the stem.
10. 10. The anti-syphon device of claim 1, wherein each of the plurality of seals comprise an O-ring shaped seal.
11. 11. The anti-syphon device of claim 1, wherein each of the plurality of seals are composed of tungsten carbide.
12. 12. The anti-syphon device of claim 1. wherein all seals are metal-to-metal seals.
13. 13. The anti-syphon device of claim 1, wherein all seals are static.
14. 14. A chemical injection mandrel comprising: a mandrel comprising a central lumen extending therethrough; a housing coupled to the mandrel; a connection port coupled to the housing that fluidly connects a control line to the chemical injection mandrel, wherein the control line controllably communicates chemicals under total injection pressure; an anti-syphon device disposed within the housing comprising: a sealing chamber comprising: an inlet port disposed on a top distal end of the sealing chamber that fluidly connects the sealing chamber to the communication port disposed on a side of the sealing chamber that fluidly connects the sealing chamber to a double check valve section, and a first translation port disposed on a bottom distal end of the sealing chamber that permits axial translation of an engagement portion of a stem; a sealing section disposed below the sealing chamber comprising: a plurality of seals disposed about the sealing section that permits axial translation of the engagement portion of the stem, and a second translation port disposed on a bottom distal end of the sealing section that permits axial translation of the engagement portion of the stem; a power section chamber disposed below the sealing section comprising: a fluidly isolated power spring disposed about a spring interface portion of the stem, and a third translation port disposed on a bottom distal end of the power section that permits axial translation of the spring interface portion of the stem; and an isolation chamber disposed below the power section chamber comprising a membrane in fluid communication with an annular fluids port that is fluidly connected to an annulus surrounding the mandrel, wherein the membrane communicates annular pressure to a bottom distal end of the stem, without fluid communication, to the power section; and the double check valves disposed within the housing below the anti-syphon device comprising a plurality of check valves that fluidly connect the sealing chamber to an interior of the central lumen of the mandrel when opened.
15. 15. The chemical injection mandrel of claim 14, wherein the sealing chamber is fluidly isolated from the sealing section.
16. 16. The chemical injection mandrel of claim 14, wherein the sealing section is fluidly isolated from the power section.
17. 17. The chemical injection mandrel of claim 14, wherein the power section is fluidly isolated from the isolation chamber.
18. 18. The chemical injection mandrel of claim 14, wherein when the total injection pressure consists only of hydrostatic head pressure and a tubing pressure is not sufficient to cause the double check valves to close, communicated annular pressure provides an assist to the power spring of the power section chamber to overcome the hydrostatic head pressure and cause the stem to axially translate upward until a stem tip is on seat, thereby preventing a sy phoning of chemicals.
19. 19. The chemical injection mandrel of claim 14, wherein undernormal operating conditions when the total injection pressure exceeds a tubing pressure, a positive pressure differential causes the stem to axially translate downward such that a stem tip is moved off seat, thereby permitting chemicals to flow through the sealing chamber to the double check valves and an the interior of the central lumen of the chemical injection mandrel.
20. 20. The chemical injection mandrel of claim 14, wherein undernormal operating conditions when the total injection pressure is less than a tubing pressure, a negative pressure differential causes the double check valves to close and causes the stem to axially translate upward until a stem tip is on seat, thereby preventing chemical injection.

Description

ANTI-SYPHON DEVICE AND CHEMICAL INJECTION MANDREL BACKGROUND OF THE INVENTION [0001] In offshore oil production, the subsurface environment presents unique challenges, including high pressures, elevated temperatures, corrosive fluids, and the potential for formation damage, all of which can compromise well integrity and reduce hydrocarbon recovery rates. Chemical injection through downhole chemical injection mandrels addresses these issues by enabling the targeted delivery of specialized chemicals directly into the wellbore or reservoir. For instance, corrosion inhibitors arc injected to form protective films on metal surfaces, preventing degradation from acidic gases like carbon dioxide and hydrogen sulfide that are often present in produced fluids; this is crucial in offshore wells where tubing and casings are exposed to seawater ingress or reservoir brines, potentially extending equipment life and averting costly failures. Similarly, scale inhibitors work by disrupting the crystallization of minerals such as calcium carbonate or barium sulfate, which can precipitate due to pressure drops or temperature changes during production, thereby maintaining open flow paths and avoiding blockages that could necessitate expensive workovers or acid treatments. [0002] Beyond corrosion and scaling, chemical injection serves to combat other production impediments common in offshore scenarios, such as paraffin wax deposition and gas hydrate formation. Paraffin inhibitors or pour-point depressants are deployed to modify the wax crystal structure, ensuring that hydrocarbons remain fluid even in cooler subsea conditions, which is particularly vital in deepwater operations where temperatures can drop rapidly along flowlines. Hydrate inhibitors, like methanol or monoethylene glycol, are injected to lower the freezing point of water in the produced fluids, preventing the formation of ice-like hydrates that can plug pipelines and cause operational shutdowns — events that are especially risky in remote offshore locations due to limited access for interventions. By integrating chemical injection mandrels into the production tubing, operators achieve precise dosing at optimal depths, controlled from the surface via capillary lines, which not only enhances treatment efficacy but also minimizes chemical usage, reduces environmental impact from overboard discharges, and optimizes overall production economics in high-stakes offshore environments. [0003] Furthermore, in mature offshore fields, chemical injection plays a pivotal role in enhanced oil recovery techniques, such as polymer or surfactant flooding, where mandrels facilitate the introduction of viscosifying agents or interfacial tension reducers to mobilize trapped oil. This targeted approach improves sweep efficiency in heterogeneous reservoirs, boosting recovery factors that might otherwise plateau. The purpose extends to safety and regulatory compliance, as effective chemical management helps prevent uncontrolled releases or equipment breaches that could lead to environmental hazards in sensitive marine ecosystems. Overall, downhole chemical injection via chemical injection mandrels represents a proactive strategy in offshore well management, balancing operational reliability, cost efficiency, and sustainability while adapting to the dynamic conditions of deepwater production. SUMMARY OF THE INVENTION [0004] According to one aspect of one or more embodiments of the present invention, an anti-syphon device for a chemical injection mandrel includes a sealing chamber having an inlet port disposed on a top distal end of the sealing chamber that fluidly connects the sealing chamber to a connection port, a communication port disposed on a side of the sealing chamber that fluidly connects the sealing chamber to a double check valve of the mandrel via a communication path, and a first translation port disposed on a bottom distal end of the sealing chamber that permits axial translation of an engagement portion of a stem, a sealing section disposed below the sealing chamber having a plurality’ of seals disposed about the sealing section that permits axial translation of the engagement portion of the stem, and a second translation port disposed on a bottom distal end of the sealing section that permits axial translation of the engagement portion of the stem, a power section chamber disposed below the sealing section having a fluidly isolated power spring disposed about a spring interface portion of the stem, and a third translation port disposed on a bottom distal end of the power section that permits axial translation of the spring interface portion of the stem, and an isolation chamber disposed below the power section chamber having a membrane in fluid communication with an annular fluids port that is fluidly connected to an annulus surrounding the mandrel, wherein the membrane communicates annular pressure to a bottom distal end of the stem, without fluid communication, to the