Introduction 14kms wide. Neelam field consists of

Introduction

 

Hydrocarbon exploration has been one of the key
business for the growing economies that world has witnessed in the recent past.
Finding for oil and gas accumulations or producing efficiently once found,
requires sound understanding of the geology and geophysics of the area, as well
as strong command on the other interdisciplinary subjects. The growth of new
technologies and specialized software has given great freedom for visualizing
the subsurface in different domains restricting to their suitable purposes.
Introduction of 3-D seismic has indeed revolutionized the oil and gas industry,
helping to deal with geological complexities and provide a good subsurface
image. A proper understanding of seismic data is necessary precursor to seismic
interpretation.

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The given project is of Mumbai offshore basin which is
located on the western continental shelf of India between Saurashtra basin in
NNW and Kerela Konkan in south. The basin falls under the category I, which
implies that the basin has proven commercial productivity. It covers an area of
about 116,000 km2 from coast to 200 m isobaths.

Neelam field was discovered in January 1987
and is located about 45kms west of the Mumbai coast and is the third largest
field after Mumbai High and Heera fields of the western off shore basin of
India. The field is about 28kms long and 14kms wide. Neelam field consists of
14 exploratory wells, 93 oil producers and 24 water injector well so far.

 

Method and Theory

 

Seismic
technology is used throughout the life of the field cycle during exploration/
appraisal, development and production stages. Establishing the link between the
well-log data and seismic data is the key in extracting the relevant
information from 3D seismic cubes. Tying the seismic data to the well-log data
is used to understand the seismic signature of the reservoir and to interpret
the reservoir structure. It is used to generate reasonable models and
predictions about the properties and structures of the subsurface.

Relevant 3D seismic data over the area of interest

                                                  

                                      a.                                                                                 b.

Figure 1 a. 1: Location map of western off-shore Basin; b. Stratigraphy of Mumbai offshore Basin

 

 

 

Conclusions

 

The objective of this paper is “Prospect generation
and identification of suitable location for drilling by interpreting subsurface
geological and geophysical data – 3D seismic data of Western offshore basin
Neelam Field”. 3D Post stack time migration (PSTM) Seismic data has been used
for detailed analysis. The data volume used is 510 sq.km. and two well data
were used. Identification of well markers and log correlation was done to
understand the regional architecture. Well to seismic tie was done by
generating synthetic seismograms. Then horizons on seismic data were tracked by
seed point tracking method and manual method in volume, based on well to
seismic tie. Different attributes were generated to identify fault patterns in
the area. Time structure maps and depth maps were generated for correlated
horizons. Inversion volume was generated and calibration was done by using
impedance logs of the drilled well. Different attributes were generated to
identify stratigraphic features such as spectral decomposition and RMS
amplitude, two prospective locations for the hydrocarbon exploration were
identified.