Jet Pump Drilling Assembly With Pressure Barrier for Underbalanced Drilling
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Solution Overview
Problem
Conventional drilling methods cause formation damage due to overbalanced conditions, leading to irreversible damage to shale reservoirs and reduced hydrocarbon production, and existing underbalanced drilling techniques fail to maintain underbalanced conditions consistently, especially in front of the drill bit, resulting in fines migration and clay mineral swelling.
Innovation Solution
A jet pump drilling system that maintains underbalanced conditions by creating a vacuum in front of the drill bit and using a pressure barrier to separate the suction and discharge sides of the jet pump, allowing formation fluids to flow into the wellbore and lubricate the drill bit, while preventing drilling fluid from entering the formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If overbalanced drilling is used to prevent blowouts, then well control is improved, but formation damage occurs due to high pressure drilling mud entering formation pores
Solution Approach 1:
The patent inverts the conventional drilling approach by using underbalanced drilling instead of overbalanced drilling. A jet pump creates negative pressure in the annulus, causing formation fluids to flow into the wellbore rather than drilling mud being forced into the formation. This reversal of pressure differential prevents formation damage while maintaining well control through the jet pump system.
Solution Approach 2:
The patent changes the pressure parameter from positive (overbalanced) to negative (underbalanced). The jet pump maintains a pressure differential where the annulus pressure is lower than formation pressure, creating a suction effect that prevents drilling mud from entering formation pores while still allowing effective cuttings removal and well control.
2Object-affected harmful factors
If underbalanced drilling is used to prevent formation damage, then formation permeability is preserved, but fines migration and clay mineral swelling occur due to inconsistent underbalanced conditions
Solution Approach 1:
The jet pump system provides continuous feedback control of annulus pressure. The pump rate and power fluid flow are adjusted based on formation pressure conditions to maintain consistent underbalanced conditions. This feedback mechanism prevents pressure fluctuations that would cause fines migration and clay swelling while preserving formation permeability.
Solution Approach 2:
The jet pump operates continuously during drilling to maintain constant negative pressure in the annulus. This continuous action ensures consistent underbalanced conditions throughout the drilling process, preventing the pressure variations that cause fines migration and clay mineral swelling, while continuously preserving formation permeability.
3Duration of action of stationary object
If drilling mud is used to cool and lubricate the drill bit, then drill bit life is extended, but formation damage occurs due to high pressure mud entering formation
Solution Approach 1:
The jet pump acts as an intermediary that enables drill bit cooling and lubrication without using high-pressure drilling mud. Formation fluids drawn into the wellbore provide natural cooling and lubrication, while the jet pump maintains the pressure differential that prevents drilling mud from entering the formation, thus protecting formation permeability.
Solution Approach 2:
The system uses formation fluids themselves to cool and lubricate the drill bit through the natural suction created by the jet pump. This self-service approach eliminates the need to force drilling mud into the formation for cooling and lubrication, thereby preventing formation damage while still extending drill bit life through effective cooling and lubrication.
4Reliability
If heavy drilling mud is used to prevent blowouts, then well control is improved, but hydrocarbon production is reduced due to formation plugging
Solution Approach 1:
The patent inverts the conventional approach by using underbalanced drilling with a jet pump to prevent blowouts instead of overbalanced drilling with heavy mud. The negative pressure in the annulus prevents blowouts by controlling formation fluid flow into the wellbore, while simultaneously preventing formation plugging, thus preserving hydrocarbon production capacity.
Solution Approach 2:
The patent changes the pressure parameter from positive to negative, using underbalanced conditions to achieve both blowout prevention and preserved productivity. The jet pump maintains annulus pressure below formation pressure, preventing heavy mud from plugging formation pores while still providing adequate well control through the pressure differential.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach minimizes formation damage, enhances hydrocarbon production during drilling, reduces drill bit wear, and increases the rate of penetration by maintaining underbalanced conditions, eliminating the need for hydraulic fracturing and reducing costs and time.
Implementation Method 1
A pressure barrier is provided surrounding the jet pump stabilizer between the suction side of the jet pump and the discharge side of the jet pump
Implementation Method 2
A pressure barrier is provided surrounding the jet pump stabilizer between the suction side of the jet pump and the discharge side of the jet pump
Implementation Method 3
allowing formation fluids to flow into the wellbore and lubricate the drill bit, while preventing drilling fluid from entering the formation
Data Source
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AI summary
Disclosed herein are various embodiments of methods and systems for drilling a wellbore into an oil or gas production zone to prevent formation damage in the reservoir using underbalanced or near-balanced drilling techniques, wherein a jet pump drilling assembly is used to create a vacuum around the drill bit. The design of this jet pump drilling assembly prevents the flow of all drilling/power fluid from entering a drill bit Only fluids from the reservoir are allowed to enter the drill bit. The assembly includes a barrier to ensure that no drilling/power fluid discharged from the jet pump located above the drill bit can flow back around to the jet pump jet pump suction ports located in the drill bit thus preventing any drilling/power fluid from ever contacting the drill bit.