The Subsurface Maps and their Applications in the Oil Industry
DEPARTMENT OF GEOLOGY
Seismic interpretation data and applications are the key element of a rapid technological evolution in the remote sensing of the subsurface maps that has resulted in geoscientists movement from data poor to data rich Stewart, S. A. 1999. The proliferation of subsurface data has profoundly affected the productivity of oil exploration of industry within last two decade. This is radically improved of the ability to predict what lies beneath the earth surface, exploration and production. Log in construction maps (well) are the supplemented by 2-D data (seismic section and maps) in the 1950s and by 3-D seismic data from the 1970s onwards Davies R. I., Bell B. R. and shoulders S. (2002). However, the evolution of the point are the essentially dealt with a seismic constructions maps without the used of fourth dimension-time and the advent of a recent recorded change in the subsurface due to hydrocarbon extraction overtime. Today, exploration involves the extraction of more geological information from the seismic signals than ever before (Leadholm et al 1985).
LIST OF FIGURES
v Contour map showing control points before and after contouring.
v Isopach map showing Drilled thickness vs. actual bed thickness.
v Isochare map showing Drilled thickness vs. actual bed thickness shown above.
v Isochare map showing colors units.
v A cross sections showing log correlation technique.
v Top & Cross-sectional views of an Isopach map of the thickness of sediments between an unconformity and basement.
v Seismic constructions showing a profile and interpretation from mentawai forearc basin source
v Log in constructions showing a constant thickness layer in drilling at different angles by three well (Isopach vs Isochare map
v Depth structure and Isopach map.
v Log construction of Isopach/Isochore map.
v The diagram illustrating correlation of depth lithologies at various depth.
v Geological sketch showing map of the study area (modified after fey base et al 1987)
TABLE OF CONTENT
List of figures
Table of contents
1.2 Basic Definition
2.0 Types of subsurface maps
2.1 Structure contour maps
2.2 Isopach maps
2.3 Isochore maps
2.4 Cross sections
3.0 Petrophysics/seismic interpretation data
3.1 Use of seismic in constructing structure Isopach maps
3.2 Use of Log in constructing Isopach/Isochore maps
4.0 Application of subsurface maps
Subsurface maps: A case study from Geofizika in Southeastern Cameroon Area.
Subsurface maps are perhaps the most important vehicle used to explore for undiscovered hydrocarbons and to develop proven hydrocarbon reserves. However, the subject of subsurface mapping is probably the least discussed of interpretation and the construction of structure/Isopach maps, yet most important aspect of petroleum exploration and development. As a field developed from its initial discovery, a large volume of well, seismic and production data are obtained. With these data, the accuracy of the subsurface interpretation is improved through time.
The most accurate interpretation for any specifics oil and gas field can be prepared only after the field has been extensively drilled and most of the hydrocarbons have been depleted. However accurate and reliable subsurface interpretations and maps are required throughout all exploration and development activities.
1.2 BASIC DEFINITIONS
1. Surface mapping: Is a way to visualize various geologic and hydrologic features in any dimension for a 1-D cross section to a 4-D production map.
2. Seismic data: is a method of exploration, geophysics that used the principles of seismology to estimate the properties of the earth subsurface from reflected seismic waves.
3. Seismic interpretation: Is the determination of the geological significance of seismic data.
4. Seismic stratigraphy: Is a techniques for interpreting stratigraphic information from seismic data.