The Development of Gps Network in Cambay Basin, India

Senthi Kumar and Arunkumar Chauhan
ONGC, Baroda, India

Cambay Basin situated on the western side of India, is a north - south oriented basin covering whole of Gujarat, India.

The Cambay Basin GPS network consists of 112 stations and one GPS stations serving approximately 170 sq.km. The GPS network survey was executed on the existing Survey of India (SOI) Great Triangulation Stations (GTS ) to approximately estimate seven parameter datum conversion coefficients between WGS-84 and Indian datum, Everest 1830 and to establish a primary high accuracy GPS network with ITRF connection in Cambay Basin for seismic data acquisition in ONGC.

The GPS network survey measurement made by Leica GX1230 receivers. Five Network stations were connected with International GPS Stations (IGS) located at Bangalore & Hyderabad- India, Kitab-Uzbekistan and Bishkek-Kyrghyzstan to obtain precise coordinates in International Terrestrial Reference Frame ( ITRF 2000) in the order of sub centimeter accuracy.

Entire GPS network was then processed and adjusted by Leica Geo Office (version 1.1 ) software to obtain network coordinates in the order of centimeter accuracy.

EGM 96 Geoid Model was used to obtain precise orthometric heights of all network stations in the order of cm accuracy and cross checked with SOI Bench Marks.

Since Cambay Basin is falling in both Grid II A and Grid III A of Lambert projection, the same is being used for northern and southern portion respectively.

With precise GPS Network coordinates & elevation and using same transformation parameter for the whole Cambay Basin, consistent and high accuracy positioning can be achieved right from exploration to deep drilling operations.

Project summary including field data collection, IGS connection, baseline processing techniques, network adjustment techniques, projection used and results obtained will be discussed in detail.

Presentation GEO India Expo XXI, Noida, New Delhi, India 2008©AAPG Search and Discovery