Borehole Seismic Fundamentals and Introduction to Advanced Techniques
This course has 6 sections. The course moves from giving a basic understanding of the most common surveys towards the newest techniques being developed to solve modern problems. 1. Introduction to Vertical Seismic Profiling The VSP techniques used in industry are introduced. Basics of wireline acquisition, and an introduction to fiber based acquisition are covered. This section gives a brief overview of the value of all the commonly used borehole seismic techniques, from checkshot through to 3D VSP. 2. The Basics Checkshot (velocity survey) and zero-offset VSPs are widely used, are simple to acquire and process, and have huge value. This section will describe acquisition, processing and interpretation of these basic, but possibly the most important, surveys. 3. 2D and 3D Imaging This section will focus on designing and interpreting walkaway VSP and 3D VSP surveys. Down-hole receivers create the opportunity for higher resolution images than surface seismic can provide, and can provide images in poor seismic imaging areas, or images where surface access is difficult. Advanced processing techniques will be discussed. Specifics of survey planning and acquisition will be covered. 4. Anisotropy and More The anisotropy module will focus on extracting VTI and HTI anisotropy parameters from walkaway VSP and 3D VSP surveys. Seismic may be improperly imaged due to poor anisotropy assumptions. Stress and fracturing information may be deduced from seismic and validated with VSP. Having receivers down-hole and sources at the surface creates an ideal opportunity to measure anisotropy in-situ. Ground truth measurement of AVO can be made with receivers downhole, this section describes the various VSP AVO techniques in common use. Downhole arrays are also ideal for locating multiple generators and measuring Q which we cover in this section. 5. Reservoir Monitoring and Reservoir Properties This section focuses on time-lapse 3D VSP, which can observe reservoir changes with a greater precision than is possible with surface seismic. There is an overview of fracture detection and orientation with VSPs. Elastic FWI is being developed to measure the reservoir’s elastic properties, and will be briefly covered. A discussion on very high resolution imaging and tomography with Crosswell seismic finishes the module. 6. Advanced Acquisition Technology marches forward as limitations are reached in wireline acquisition. Putting the receivers in the drill string to get real-time VSPs (while drilling) is becoming routine. Optical fiber (DAS) recording is an emerging technology which enables efficient, fit-for-purpose VSP surveys with cost benefits over traditional wireline technology.
Upon completion of the course, participants will know the basics of acquiring and processing borehole seismic data. They will also be familiar with the latest borehole seismic techniques in: • High resolution imaging using 2D and 3D VSP surveys; • Anisotropy determination and fracture analysis; • Reservoir monitoring using time lapse VSP and crosswell seismic; • Alternative acquisition schemes such as SWD and DAS. Participants will have a better understanding of the role of borehole seismic techniques in hydrocarbon exploration and production. They will be able to more knowledgeably participate in the design, planning and execution of advanced surveys and be comfortable with the interpretation of these surveys.
The course will contain the following modules: 1. Introduction to Vertical Seismic Profiling (1.5hrs) 2. The Basics (2 hrs) a. Checkshot VSP b. Zero Offset VSP 3. VSP Imaging: 2D and 3D Techniques (2 hrs) a. Survey design and modeling b. Processing - model building, tomography, imaging techniques (Kirchhoff, RTM) c. 2D imaging - Offset VSP, Walkaway VSP d. 3D imaging 4. Anisotropy and More (3 hrs) a. Measuring anisotropy with walkaway and 3D VSPs -VTI and HTI, fractures b. AVO Analysis c. Techniques to locate multiple generators with VSP data d. Q estimation and Q compensation with VSP data 5. Reservoir Monitoring and Reservoir Properties (1.5 hrs) a. Time Lapse 3D VSP for reservoir monitoring b. Elastic FWI (VSP Inversion) 6. Advanced Acquisition (1.5hrs) a. Seismic while drilling b. Distributed Acoustic Sensing Timing of sections may change.
The course is targeted toward those who have a basic understanding of surface seismic acquisition and processing, but only limited knowledge of borehole seismic. The course is designed to help participants identify borehole seismic solutions to common seismic interpretation problems. It is also be useful for those geophysicists needing higher resolution images than surface seismic can provide, and those geophysicists who need to validate seismic processing parameters and imaging models using borehole seismic. Lastly, the course is relevant for geophysicists wanting to learn how to use borehole seismic as a cost-effective reservoir monitoring tool.
Participants are assumed to have knowledge of seismic response to earth reflectivity. Participants should be aware of common well logging services.
About the Instructor
Allan Campbell graduated in 1984 from the Northern Alberta Institute of Technology in Edmonton with a diploma in Earth Resources Technology and, after a spell in Dresser Atlas, graduated in 1990 from the University of Calgary with a BSc., majoring in Geophysics. In 1990, he started his 25-year career at Schlumberger in Calgary. Skills were developed in borehole seismic processing starting from basic check-shots up to the most complex 3D VSPs. In 1997, he moved to Houston Texas, to open a new borehole seismic processing center. The center rapidly evolved into a global center of excellence for VSP processing. Campbell helped Schlumberger fully develop 3D VSP processing capabilities. 2010 to 2015 saw the development of many innovative techniques. The integration of borehole seismic data into the processing of surface seismic, to improve the resolution and depth control in seismic images, was finally realized. VSP is now routinely used to detect and characterize fractures, to estimation of the elastic properties of rocks, and to monitor the changes in reservoirs due to both enhanced recovery methods and storage of CO2. From 2016 to the present, Campbell has been working as a geophysical consultant with VSP Consultants LLC. Projects have included work for major operators and service companies, supervising VSP processing projects. Interesting work is also being done on drill bit seismic in hard rock mining environments. VSP Consultants is also offering borehole seismic training courses to the oil and gas industry.