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Interactive Structural Analysis – Quantitative Interpretation of Complex Structures Imaged in
Seismic Data
Interpretation of complex structures using seismic and well data is often challenging because data are
incomplete or ambiguous. However, an understanding of earth processes can constrain our
interpretations. Specifically, we have a good quantitative understanding of how fold shapes and areas
are related to fault geometries and displacements. Consequently we can combine forward modeling,
structural restoration and related techniques such as area-depth analysis to constrain (1) fault shapes
and displacements, (2) correlations across faults, (3) structural and stratigraphic history, and (4) strain
within structures.
We illustrate this approach using software that works in a flexible, highly interactive fashion, with all
structural computations and analyses being displayed instantaneously as the earth scientist modifies
their interpretation. Valuable structural analyses can be performed by the specialist and non-specialist
alike, at the “speed of thought” rather than at the speed of a typical technical project.
We will discuss the technical underpinnings of the software and illustrate its use in real-time with
worldwide and California case studies, most of which combine structural development and sedimentary
deposition. We also analyze a deepwater growth structure in detail to show how integration of
multiple-fault trishear modeling, restoration, and area-depth analysis can contrain fault shapes to
depth, fault displacement histories, and internal strain at the reservoir scale. This example illustrates
how the flexible combination of structural techniques yields more useful results than single techniques
such as balanced section construction.
We note that many 3D interpretations in complex structural regimes are begun and even completed
without understanding the regional structural kinematics. Misinterpretations of fault shape and crossfault correlation often propagate, becoming expensive to correct or even leading to errors that impact
exploration and development success. We advocate that integrated structural analyses of key profiles
should be perfomed prior to detailed interpretation of 3D seismic volumes, as well as at intermediate
stages during interpretation. The use of fully interactive structural analysis software makes this
approach both feasible and attractive.
Alan Nunns
Dr. Alan Nunns is the founder and president of StructureSolver, a company which focuses on the
development of innovative geotechnical software.
Prior to founding StructureSolver, Alan’s 24 years career with Chevron included positions of increasing
responsibility in research, operations and technology management.
Alan was a principal developer for Chevron’s first 2D interactive seismic interpretation system, which
included many novel geological and geophysical features. He was the co-founder of Chevron’s structural
geology research team, leading research and development in quantitative structural modeling and the
seismic interpretation of complex normal fault systems. He led the fault framework definition for
Chevron’s 3D acreage in Nigeria, which contributed to several very large discoveries. He managed earth
science operations for Chevron Nigeria’s largest asset area. His team planned a full schedule of
successful workovers and conventional and horizontal development wells, including the well with
highest net oil pay (350 ft.) and the well with highest initial oil flow rate (6000 barrels per day) in
Chevron Nigeria’s history. During his tenure the asset area increased production by 20% to over
135,000 barrels of oil per day, arresting previous declines.
In 1999, Alan became General Manager of Global Technology and Strategy for Chevron. In this job he
helped steer Chevron’s IT through the global standardizations of infrastructure and applications that
accompanied the Texaco and Unocal mergers.
Alan has a BSc Honors (1st Class) in Geology from the University of Auckland and a PhD in Marine
Geophysics from the University of Durham, U.K, where he was a Commonwealth Scholar from NZ.