Seismic While Drilling (SWD), is a technology that integrates seismic measurement into drilling operations. SWD combines traditional seismic methods with the real-time data provided by Measurement-While-Drilling (MWD) systems, enabling the prediction and avoidance of potential hazards ahead of the bit and can provide a continuous update of the subsurface model in real-time.
Applications of SWD
SWD technologies provide crucial information that can enhance drilling efficiency, improve safety, and optimise well placement. There are several key applications:
Reducing depth uncertainties: SWD reduces uncertainties by updating the seismic model in real-time, leading to better well execution and reduced risks of missing the target zone. The uncertainty in the depth of targets determined by surface seismic measurements, often leads to wells not being optimally positioned within the intended reservoir (ref) (ref).
Geosteering and Well Placement: Near real-time VSP data helps visualize events ahead of the bit, enabling timely decisions if data quality permits. By providing real-time seismic data, SWD can help in geosteering – the process of adjusting the drill bit’s direction based on the geological information gathered while drilling. This ensures optimal well placement within the reservoir to maximize hydrocarbon recovery and avoid predicted hazards.
Hazard Identification and Avoidance: SWD technologies can identify potential hazards such as gas pockets, fault zones, and high-pressure formations. Early detection of these hazards allows for proactive measures to avoid drilling-related problems like stuck pipe incidents and kicks, enhancing drilling safety (ref).
Casing and Well Completion: The technology assists in determining the optimal setting for casing points and the overall completion strategy (ref).
Cost Reduction and Efficiency Improvement: By improving the accuracy of well placement and reducing the risks of drilling hazards, SWD technologies can significantly reduce drilling costs and improve overall drilling efficiency. Real-time data acquisition and interpretation mean that decisions can be made quickly, reducing non-productive time.
Time-lapse Seismic Monitoring: Time-lapse seismic monitoring involves acquiring seismic surveys at different times over the same area to observe changes in the subsurface, typically related to fluid movements or reservoir compaction due to production activities. SWD can be used for time-lapse (4D) seismic monitoring, allowing operators to observe changes in the reservoir during the production phase. This is valuable for managing reservoir performance and planning secondary recovery methods (ref)
Relief well drilling – The Seismic While Drilling (SWD) has been proposed as a novel approach for more accurately locating and intersecting a blowing wellbore when drilling relief wells, independent of magnetic materials or casing presence. By using a surface seismic source and seabed receivers, SWD could enable real-time, non-intrusive monitoring of well paths, potentially allowing for intersections below the casing shoe. Additionally, SSWD offers potential benefits in conventional well killing by providing precise wellbore positioning, which could streamline the drilling of relief wells (ref).
History of SWD
The history of Seismic While Drilling (SWD) technology reveals a history which has evolved over decades:
Early Concepts and Development
The concept of utilising seismic data to guide drilling operations is not new. However, the practical application of acquiring seismic data while drilling (as opposed to before drilling operations commence) began to gain traction in the late 20th century. Early attempts at SWD were primarily focused on listening to the drill bit as a seismic source. The drill bit, when drilling, naturally generates acoustic energy that propagates through the earth and can be recorded by geophones placed on the surface or in nearby wells.
1980s to 1990s: Formalisation and Technological Advances
In the 1980s, the potential of using the drill bit noise for seismic imaging began to be more formally explored. This period saw the development of techniques to use the acoustic energy generated by the drill bit to create real-time images of the subsurface. These early efforts were aimed at enhancing the understanding of the geological structure around the drill bit to make on-the-fly decisions about drilling direction and to detect hazards.
By the 1990s, advances in digital signal processing, along with improvements in hardware such as geophones and accelerometers, allowed for more sophisticated analysis of the seismic signals generated by drilling. The introduction of Logging While Drilling (LWD) technology, which integrates measurement tools within the drill string, provided new opportunities for SWD by enabling the collection of seismic data directly from the borehole environment.
2000s: Integration and Commercialization
The early 2000s saw further integration of SWD technology with LWD systems, leading to the commercial availability of SWD services. These services allowed for the acquisition of Vertical Seismic Profiles (VSP) while drilling, using either the drill bit itself or dedicated seismic sources deployed at the surface or in offset wells. This period also saw the development of technologies that could transmit seismic data to the surface in real time, enabling immediate interpretation and decision-making.
2010s to Present: Refinement
In the last decade, SWD technology has continued to be refined, with improvements in data quality, processing algorithms, and operational efficiency. The industry has also explored the use of SWD for applications beyond traditional hydrocarbon exploration, such as geothermal energy development and carbon capture and storage (CCS) projects.
SWD technology involves acquiring seismic data in real-time as the drilling progresses. The system uses downhole tools that are capable of recording seismic waves generated by a source at the surface or near the wellbore. These tools are part of the drilling assembly and move with the drill bit, capturing data that is either transmitted to the surface in near real-time or stored in memory for later retrieval.
Real-world applications
The following case studies shed light on the real-world application of SWD technology, showcasing the role the technology has played for operators solving specific challenges, enhancing operational efficiency and the decision-making process:
Seismic Measurements While Drilling in the Deepwater Gulf of Mexico (ref): This case study showcases how seismic uncertainty significantly influences well construction costs. SWD is shown to be instrumental in improving decision-making for casing point selection by providing real-time depth predictions. Furthermore, SWD is shown to assist in calibrating LWD sonic data and creating VSP images that match surface seismic data, demonstrating its effectiveness in the ultra-deepwater Gulf of Mexico through real-time depth predictions and significant look-ahead capability.
Integrated LWD and Wireline Borehole Seismic in Deepwater Indonesia (ref): The Timpan-1 well in the Andaman Field used a unique blend of LWD and wireline VSP to enhance safety and reduce exploration risk. SWD technology informed geostopping decisions, allowing accurate casing placement above the carbonate reservoir. The integration of SWD and wireline VSP data provided a comprehensive depth and velocity understanding, showcasing how combining these technologies can mitigate significant subsurface uncertainties.
Reducing Target Uncertainties with SWD in the Andaman Sea (ref): ONGC utilized SWD technology for the first time in their Andaman Sea deepwater drilling campaign to guide real-time drilling decisions. The technology enabled the acquisition of real-time checkshot data without disrupting drilling, refining the pre-drill velocity model and improving target prognosis depths. This application of SWD eliminated the need for additional casing runs and confirmed drill bit positions, demonstrating significant cost and time efficiency.
First Application of SWD in HTHP Offshore Exploration in the South China Sea (ref) (ref): In the challenging HTHP environment of the South China Sea’s D block, SWD was applied for the first time to accurately predict target zone depths and monitor pore pressure ahead of the bit. This approach provided an integrated solution for real-time updates on depth prediction and pore pressure monitoring, ensuring safe drilling within a narrow mud window and successful well completion.
Rank Wildcat Drilling Risks Reduced in Ultra Deepwater Offshore Namibia with SWD (ref): Utilizing high-tech LWD suites, including SWD, significantly reduced drilling risks and uncertainties in offshore Namibia. The technology allowed for accurate target depth prediction, safe casing placement, and optimized mud weight windows. Additionally, Formation Pressure While Drilling Technology calibrated the pre-drill pore pressure model, showcasing SWD’s ability to navigate complex drilling environments effectively.
Value of LWD Seismic Technology in Offshore Malaysia Exploration (ref): This case highlights the application of LWD seismic technology in offshore Malaysia to address challenges such as expected pressure ramps and gas chimneys. Real-time VSP imaging and velocity data from a dual-tool LWD seismic setup enabled precise casing point selection and well construction, eliminating the need for an additional casing string. The successful application underscores the technology’s capability to provide critical real-time data for navigating geological hazards.
Impact of Seismic While Drilling and Check Shot Processing Techniques on Drilling Trajectory Decisions (ref): Seismic While Drilling (SWD) is employed to gather Real-Time seismic checkshot data during the drilling process, aiming to reduce the risks associated with depth uncertainty and the accurate positioning of the target. The case study highlights the importance of the checkshot processing technique selection—specifically, whether to use the “Break-to-Break” or “Trough-to-trough” timepick conventions—for determining borehole seismic checkshot transit times. The choice between these techniques can significantly influence target depth predictions and drilling decisions in exploration wells. Furthermore, the study introduces a method for selecting the most suitable technique for SWD depth prediction, leveraging the predrill data available. This strategic approach to technique selection enhances the accuracy of depth predictions, thereby optimizing drilling trajectory decisions and minimising the risks associated with drilling operations.
Delineating Salt Boundaries in the Gulf of Mexico Using SWD and P/PS Waves (ref): Between 2018 and 2019, Shell conducted two Vertical Seismic Profiling (VSP) surveys in deepwater wells in the Gulf of Mexico using Seismic While Drilling (SWD) technology, employing both rig sources (Zero-offset VSP, ZVSP) and boat sources (Offset VSP, OVSP). The primary goal of these surveys was to accurately identify the boundaries between salt formations and sediment at both the base and flank of salt structures. Through the design and implementation of complex VSP surveys, carried out efficiently and cost-effectively, Shell developed an innovative analysis and processing approach. This method combined P wave data from sediment and salt proximity with converted PS wave data for salt proximity, to delineate the salt boundaries. Utilising data from the 2018 SWD-VSP survey, the integrated results enabled the definition of salt boundaries with enhanced accuracy and confidence. This successful application of SWD in VSP surveys provided Shell with considerable business and technical benefits, illustrating the method’s potential for precise subsurface exploration.
Operations and Procedures
One of the main reasons that the SWD service is not utilised by operators (besides perceived costs) is concerns over operational efficiency and how the process of acquiring data whilst drilling may impact drilling (ref). Efficiency of operations has improved over the years as methods and processes have been refined and operators become familiar with managing the logistics and data acquisition processes.
Planning
Initial preparations are crucial for the success and data quality of the job, necessitating careful consideration of well geometry and the seismic source’s placement. Understanding the data acquisition strategy—whether during drilling entry, active drilling, or exit—is essential for the engineer to configure the tool effectively well in advance. Subsequently, the tool is set up, and both surface and downhole timing mechanisms are aligned.
Considerations at the planning phase include (ref):
- Ray trace modelling
- Real time processing
- Acquisition density
- Site survey
- Rig setup
- Drilling personnel training
- Seismic Source handling
- Network/application performance
- Decision making processes/resources
Below is a typical SWD running procedure (ref)
- Synchronization of Surface and Downhole Clocks: Before starting the operation, it’s vital to ensure that the time references are in sync.
- Running in Hole (RIH): The drill string, equipped with the SWD tools, is run into the wellbore.
- Measurement While Connection (or Half Stand): Seismic measurements are taken during connections, which is when new sections of the drill pipe are added.
- Seismic Source Positioning: The seismic source, typically located on the surface or in an offshore setting on a vessel, is positioned to send acoustic waves down the well.
- Downlink Command: A command is sent from the surface to the downhole equipment to prepare for seismic shot acquisition.
- Acquisition of Seismic Shots: The seismic source is activated, and the downhole tools record the seismic waves.
- Storing Raw Data Downhole: The data from the seismic shots is stored in the tool’s memory.
- Autonomous Detection of Source Wavelet: The downhole tool autonomously detects and characterizes the seismic source wavelet.
- Uplinking Stacked Trace: A processed, stacked trace of the seismic data is transmitted to the surface for analysis. Pulling Out of Hole (POOH) (Optional): Data can also be acquired while tripping out of the hole, providing additional information.
- Memory Dump and Processing: Once the tool is brought to the surface, a memory dump of the raw multi-component data is performed, followed by detailed data processing.
Technical Advisory
There has been a number of challenges and issues raised by operators in relation to the use of SWD, exemplified by a survey conducted by the JPT (ref):
- Quality Control and Dependability: There has been historical scepticism regarding the real-time data quality control of LWD/SWD. Reliance on data without thorough, real-time verification can be perceived as risky by some.
- Integration and Collaboration: Effective deployment of SWD technology requires closer collaboration and communication between geophysicists and drilling engineers. However, fostering this interdisciplinary approach remains a challenge.
- Narrow Application Scope: Currently, SWD applications are viewed as too limited. Expanding its uses could enhance its value but requires overcoming technical limitations.
- Technological and Knowledge Gaps: There are identified gaps in technology and expertise, especially concerning acoustics and the development of acoustic ‘ranging’ data. Addressing these gaps is essential for advancing SWD applications.
- Enabling Technologies: The development of wired drillpipe technology, like Grant Prideco’s Intelliserv system, could facilitate the transmission of large amounts of raw data essential for seismic processing. However, integrating this with SWD tools poses additional challenges.
The use of SWD services requires comprehensive planning and understanding for its effective use as a drilling decision tool. SWD’s full potential is unlocked through a holistic approach that includes meticulous planning, project management, and collaboration among drilling and subsurface teams to ensure the operation’s success without hindering drilling activities.
SWD can update the geological model in real-time, providing improved resolution, accurate depth conversion, and the flexibility for various geophysical applications like imaging salt flanks and fault planes. However, real-time communication between the rig and domain specialists are required for the data acquired to become valuable to the drilling team – in real-time. Central to the effectiveness of SWD into the drilling input is a quick turnaround of data qc and processing which can be done at the wellsite or remotely.
one&zero consultants take the data from the vendor and do independent time picking and velocity model updates continuously as drilling proceeds. This includes and inversion of the data to look ahead of the bit to the next formation of interest. When the memory data is downloaded our consultants can produce accurate lookahead VSP images. Further one&zero are able to utilise our partnership with VSProwess to enhance to processing deliverables during acquisition.
Effective communication and planning are vital for a successful SWD operation, which involves intricate system design, operational adjustments, and data processing to inform drilling decisions. The technology has shown promise, but has not reached its full potential, partly due to costs but also due to lack of awareness experience with the technology (ref).
one&zero’s domain expertise in planning and executing SWD operations can prove invaluable to operators to ensure efficient use of rig time during operational execution.
Conclusion
Seismic While Drilling technology when deployed as part of a drilling BHA can provide crucial real-time data that can greatly enhance the safety, efficiency, and success of drilling projects. The integration of seismic data acquisition into the drilling process allows for continuous updates to the subsurface model, enabling operators to make informed decisions on the fly. With the ability to predict and avoid hazards, optimize well placement, and Seismic while drilling technology presents a useful tool in the field of drilling risk management. SWD offers subsurface visibility that enables safer, more efficient, and more successful drilling operations. By providing vital information in near real-time, SWD helps mitigate risks and optimize well placement and completion.
Navigating the complexities and potential risks associated with Seismic While Drilling (SWD) operations is essential. The consulting team at one&zero, along with our partners, brings a wealth of experience in orchestrating the planning, preparation, and implementation of SWD projects. We’re here to ensure you start on the right foot, preventing avoidable errors from occurring.
If you are planning or preparing for a Seismic While Drilling operations (get in touch – [email protected])
James Bailey and VSPROWESS LTD – Many thanks for your input into this article.
