𝗪𝗲𝗹𝗹Design Planning 

1. Well Objectives and Site Selection

 

The first step in well planning is defining the well objectives. These objectives may include hydrocarbon production, water injection, geothermal energy extraction, or exploratory drilling. Site selection follows, involving geological and geophysical surveys to identify optimal drilling locations based on subsurface characteristics, reservoir potential, and environmental considerations.

 

2. Well Trajectory Design

 

Well trajectory design determines the path the wellbore will take to reach the target reservoir. Common trajectory types include:

 

Vertical Wells: Simplest design, often used for conventional reservoirs.

 

Deviated Wells: Drilled at an angle to reach targets offset from the rig location.

 

Horizontal Wells: Maximizes reservoir exposure, improving production rates.

 

Multilateral Wells: Multiple wellbores extending from a single main borehole to enhance drainage.

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Factors influencing trajectory design include formation properties, target depth, drilling constraints, and cost considerations.

 

3. Casing and Cementing Design

 

Casing and cementing are essential for well integrity and stability. The casing program is designed based on well depth, formation pressures, and expected loads. Casing strings include:

 

Conductor Casing: Provides initial well support and prevents surface collapse.

 

Surface Casing: Protects freshwater aquifers and stabilizes upper formations.

 

Intermediate Casing: Isolates unstable formations and prevents well control issues.

 

Production Casing: Facilitates hydrocarbon production from the reservoir.

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Cementing secures the casing in place and isolates different formation zones, preventing fluid migration.

 

4. Drilling Fluid Selection

 

Drilling fluids (mud) play a crucial role in wellbore stability, cooling the drill bit, and carrying cuttings to the surface. The selection of drilling fluids depends on:

 

Well depth and pressure conditions

 

Formation type and stability

 

Environmental impact considerations

 

Cost-effectiveness

 

Common drilling fluids include water-based mud (WBM), oil-based mud (OBM), and synthetic-based mud (SBM), each with specific advantages for different drilling conditions.

 

5. Well Control and Safety Measures

 

Well control is crucial for preventing blowouts and ensuring safe operations.

 

This involves: Blowout Preventers (BOPs): Installed at the wellhead to control unexpected pressure surges.

 

Kick Detection Systems: Monitoring pressure changes to identify formation fluid influx.

 

Pressure Control Methods: Including choke manifolds and kill procedures to maintain stability. 

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Below are few Key Elements & Deliverables that can be added in the WellDesign for a comprehensive Full Field Development Study.

 

• Risk & Hazards Identification & Risk Mitigation. 

• Well blow-out Simulations to replicates Well Killing & Pumping capacities while drilling & blow-out scenarios.

• Well Complexity Index assessment for high complex wells.

• Integration of well paths / well trajectories in the Geological & Reservoir Simulation Model.

• Pore Pressure & Fracture Pressure Study. 

• Managed Pressure Drilling Simulations.

• Kick influx and Well Killing Simulation / Well control modelling and simulation.

• Relief Well Planning to drill & kill the blowout well. 

• Well Integrity Management process over the full life cycle of well.

• Well Delivery Process to high quality wells on time and on budgeted time & cost.

• Development of a Well Value Assurance Process

• Potential Workover or Intervention work that may be arise during the well in production over the well life cycle. 

• Development of the Emergency Response Plan.

• Plugging and abandonment policy / guidelines for of the depleted / nonproducing / redundant wells in the field.

• Well Construction designs for high sour wells H2S & HPHT wells.

• Well / Project delivery process “Peer Assist” in the well / project delivery process. 

• Integrated, planning of drilling / projects & Drilling Performance Optimization process.

• Offset wells analysis & reviews.

• Lost Circulation Management Strategies and guidelines to avoid losses mitigating thru well design or optimization of the well trajectory and adopting special technical solutions / strategies to avoid / minimize loss circulation while drilling the wells. 

• Categorization of the Deviated wells design field such as slightly deviated, highly deviated or horizontal drilling for future well drilling concepts.

• Rig Selection criteria / Contracts Management & Supports.