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From Static to Dynamic Interpretation of Subsurface Data - A Change of Paradigm*
By
Dietrich H. Welte1, Bjorn Wygrala1, and Thomas Hantschel1
Search and Discovery Article #40058 (2002)
*Adapted for online presentation from the article by the author in AAPG Explorer (May, 2000), entitled “Static Interpretation Now Dynamic.” Appreciation is expressed to the author and to M. Ray Thomasson, former Chairman of the AAPG Geophysical Integration Committee, and Larry Nation, AAPG Communications Director, for their support of this online version.
1IES Integrated Exploration Systems, Juelich, Germany (www.ies.de; [email protected])
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General StatementThe most widespread
source for subsurface data is 2-D and, increasingly, 3-D seismic. Data
related to boreholes - such as well logs and rock samples - provide
crucial complementary and calibration parameters. In the past, and even
today, the prevailing approach in the interpretation of these subsurface
data is static. This means that great efforts are made to describe
subsurface structures and property distributions in their present state.
However, understanding and In petroleum exploration and production it is an essential requirement to understand these past geological processes - especially petroleum generation and migration - which determine whether or not a trap contains hydrocarbons. Hence, it is crucial to understand the dynamics of relevant processes responsible for the present day geological conditions. As
Static to Dynamic Process (Figures 1 and 2) The conversion of static data to a dynamic process interpretation starts with a rigorous analysis of the stratigraphic time record of the sedimentary column and by assigning absolute ages. In this way an absolute time sequence of critical geological events is derived and a conceptual geological process model is created, forming the backbone of the dynamic process interpretation and the chain of logics for a computer model. A petroleum system includes the entire hydrocarbon source, carrier, and accumulation system, and the goal must be to reconstruct the entire geological history of a petroleum system, from its origin to the present. The main focus must be on the location and 3-D configuration of drainage areas for mature source rocks through time, and on possible migration pathways to collect the corresponding hydrocarbon charge. The The
resulting dynamic
Software programs
today can provide all of this functionality. Petroleum migration
processes can be modeled in two dimensions (2-D) along geological cross
sections, but any attempt to quantify hydrocarbons in a simulated system
must be based on three dimensional (3-D) data archives and
Simulation runs that reconstruct the
geological history of a petroleum system inclusive of multi-phase
migration
Overpressure zones can be fairly well
predicted by geological process
This kind of 3-D Procedure and Logistics
Today a complete array of
technological facilities is already available to extend “classical” but
static subsurface data interpretations into dynamic process The next step is to extend the integration of the various technologies and data types to create even more value by adding synergies. It is the provision and availability of proper interfaces between the relevant software packages and intelligent tools interactively to manipulate original data and results on both sides. This step, without any doubt, will dramatically accelerate the application of more intelligent (dynamic) data interpretation tools. The cost of this type of dynamic interpretation compares favorably with, for instance, the cost of sophisticated seismic processing including attribute analysis, or obviously of drilling dry wells in deep water environments. All in all, a dynamic interpretation of subsurface data greatly improves our understanding of crucial geological processes - and it narrows down the band width of uncertainties. Furthermore, it is the ideal vehicle to integrate different geoscientific disciplines, to create real links between exploration and exploitation data archives and processing tools. The result? Logically organized work flows in interdisciplinary teams. |