Well Lifecycle: From Planning to Abandonment

The lifecycle of a petroleum well is a structured process that spans from identifying a reservoir to its final closure. Each phase requires a combination of geological, technical, and regulatory expertise to ensure safety, efficiency, and environmental compliance. This chapter details the main phases of a well’s lifecycle—planning, drilling, completion, production, and abandonment—focusing on technical aspects and regulatory requirements, such as the Authorization for Expenditure (AFE) and permits. Understanding this cycle connects geological concepts, well types, and prepares the groundwork for equipment and rig organization.

Phases of a Well’s Lifecycle

The lifecycle of a petroleum well is divided into five main phases, each with specific technical objectives and regulatory requirements to ensure project success. These phases are interdependent, and an error in one can impact the others. Below, they are described in detail.

1. Planning

Planning is the initial phase, where the technical and economic feasibility of the well is defined. It begins with interpreting geological and geophysical data, such as subsurface maps, to identify the optimal well location and trajectory (vertical, directional, or multilateral). Engineers evaluate formation properties, such as hardness and stability, to select the drill bit, drilling fluid, and casing design.

Technical Aspects:

• Geological study: Use of seismic data and prior well logs to map traps and reservoir rocks.
• Well design: Definition of depth, diameter, and trajectory, considering reservoir conditions.
• Equipment selection: Choice of rig (onshore or offshore) and tools like MWD systems.

Regulatory Aspects:

• Authorization for Expenditure (AFE): A document detailing estimated project costs, including drilling, completion, and equipment. The AFE must be approved by the operator’s management and, in some cases, partners or investors.
• Permits: Local authorities require environmental and land-use permits. For example, in the Gulf of Mexico, drilling requires permits from the Bureau of Safety and Environmental Enforcement (BSEE), which assess environmental impact and safety.

For example, in an exploratory well in Vaca Muerta, Argentina, planning includes an AFE covering the costs of a mobile rig and permits to operate in a protected area.

2. Drilling

The drilling phase involves constructing the well, penetrating geological formations to reach the reservoir. It uses a rig (conventional, mobile, or offshore) and systems like the top drive to rotate the bit and advance. Drilling fluid (mud) cools the bit, removes cuttings, and controls well pressure.

Technical Aspects:

• Bit operation: Adjustment of weight on bit (WOB) and revolutions per minute (RPM) based on formation hardness.
• Pressure control: Monitoring reservoir pressure to prevent kicks, using blowout preventers (BOPs).
• Real-time logging: MWD and LWD tools provide data on trajectory and formation properties.

Regulatory Aspects:

• Safety compliance: HSE (Health, Safety, and Environment) protocols require regular equipment inspections and emergency plans.
• Operational reports: Authorities require daily reports on drilling progress and any incidents, such as circulation losses.

In a directional well in the Permian Basin, drilling may take weeks, with constant mud adjustments to handle unstable shales.

3. Completion

Completion prepares the well for production, installing the components needed to connect the reservoir to the surface. It includes placing casing, cementing to isolate zones, and perforating the casing to allow hydrocarbon flow.

Technical Aspects:

• Cementing: Seals the annular space between the casing and wellbore wall to prevent fluid migration.
• Perforation: Holes are made in the casing using perforating guns to connect the reservoir rock to the well.
• Lift system installation: Pumps or artificial lift systems, like gas lift, are installed to optimize production.

Regulatory Aspects:

• Integrity testing: Authorities require pressure tests to verify the well has no leaks.
• Completion approval: A detailed plan must be approved, ensuring compliance with environmental regulations.

In a horizontal well in Eagle Ford, completion includes hydraulic fracturing to enhance reservoir rock permeability.

4. Production

The production phase is the core of the cycle, where the well extracts hydrocarbons to the surface. Its duration and volume depend on the well type and reservoir properties. Development wells are the most common in this phase.

Technical Aspects:

• Production monitoring: Sensors measure flow rate, pressure, and fluid composition to optimize extraction.
• Maintenance: Workover operations may be needed to clear blockages or install pumps.
• Reservoir management: Injection wells are used to maintain pressure.

Regulatory Aspects:

• Production reports: Authorities require monthly data on produced volumes and emissions.
• Environmental compliance: Spills or gas emissions are monitored, especially in sensitive regions.

In Venezuela’s Maracaibo field, production can last decades, with injection wells supporting recovery.

5. Abandonment

Abandonment occurs when the well is no longer economically viable or has fulfilled its purpose. It involves sealing the well to prevent hydrocarbon leaks and protect aquifers.

Technical Aspects:

• Sealing: Cement plugs are placed in the well to isolate all productive zones and aquifers.
• Equipment removal: Surface facilities, such as wellheads, are dismantled.
• Site restoration: In onshore operations, the land is rehabilitated to minimize environmental impact.

Regulatory Aspects:

• Abandonment plans: Authorities require a detailed plan complying with environmental regulations, such as those of the EPA in the U.S.
• Final inspections: Verification ensures the well is properly sealed to prevent long-term leaks.

For example, in the North Sea, offshore well abandonment is costly due to strict regulations and marine conditions.

The following table summarizes the lifecycle phases:

Summary

The lifecycle of a petroleum well spans from planning, integrating geological and regulatory data, to abandonment, ensuring environmental safety. Each phase—planning, drilling, completion, production, and abandonment—requires precise technical decisions and regulatory compliance, such as the AFE and permits. These concepts connect with geology, well types, and prepare the groundwork for equipment and rig organization.

Practical Exercise

1. Reflection question: Why do you think planning is a critical phase in a well’s lifecycle, and how can it affect subsequent phases?
2. Research task: Investigate an oilfield (e.g., Permian Basin) and write a paragraph describing how the drilling and completion phases are applied in its wells.
3. Technical question: Explain the purpose of the AFE and how it is used to coordinate a drilling project.

Bibliography

• Books used:

  • Hyne, N.J. (2012). Nontechnical Guide to Petroleum Geology, Exploration, Drilling & Production. PennWell Books.
    Explains the well lifecycle in an accessible manner.
  • Bourgoyne, A.T., Millheim, K.K., Chenevert, M.E., & Young, F.S. (1986). Applied Drilling Engineering. SPE Textbook Series.
    Details the technical and regulatory phases of the lifecycle.

• Recommended books:

  • Mitchell, R.F., & Miska, S.Z. (2011). Fundamentals of Drilling Engineering. SPE Textbook Series.
    A technical resource on the lifecycle and operations. Available at: https://store.spe.org/Fundamentals-of-Drilling-Engineering-P113.aspx.
  • Azar, J.J., & Samuel, G.R. (2007). Drilling Engineering. PennWell Books.
    Ideal for deepening knowledge on planning and abandonment. Available at: https://www.pennwellbooks.com/drilling-engineering/.

• Direct links:

  • SPE (Society of Petroleum Engineers): Resources on well lifecycle. https://www.spe.org/en/.
  • AAPG (American Association of Petroleum Geologists): Information on planning and abandonment. https://www.aapg.org/.
  • PetroSkills: Courses on drilling and completion operations. https://www.petroskills.com/en/training/courses/drilling-practices---dp.