Computerized Data Base for Offshore Mapping
Authors: Sheridan Dean M. 
Published: October 2008

This paper examines the creation and use of a comprehensive interactive graphics data base for both offshore and onshore areas. The computerized data base system provides the user with the capability to resolve problems involving coordinate and projection transformations, prepare accurate base maps from various sources, immediately access graphical and associated no pictorial well and shot line and shot point data, and modify or update information.

The system will be useful at any technical level, for example, by geophysicists, for detailed well and selected seismic information, or by managers, for project development. The data base can be prepared for any prospect area in the world where mapping requirements demand an accurate gobies (coordinate network) and the precise automatic placement of wells.

This paper examines the data base system's capabilities in selective display (to show only the desired data), selective mapping (to change scales and symbols), and selective retrieval and reporting (to display data listings, tabulations, totals, subtotals, and sorted output). The system can store the location of all entered data in terms of latitude and longitude and display or plot data in any projection coordinate system, such as Lambert Conformal Conic, Universal Transverse Mercator, or Oblique Mercator. A continuous display can be made over a large area and across projection and coordinate system boundaries. Examples of the graphical and no pictorial displays are included.

INTRODUCTION

Data of interest to the oil and gas industry comes in a variety of forms, such as maps, aerial photographs, computer cards, magnetic tapes and disks, survey descriptions, tables, and charts, and is available in many projections and at various scales (see Figure 1). As shown in Figure 2, an interactive graphics data base management system consolidates this volume of information into an integrated collection of data and allows access to the data by means of graphics terminals and computer-generated printouts and plots.

DATA BASE ASSEMBLY

The first step in the creation of a data base is the collection and assembly of all data sources to be entered into the system in any number of forms (e.g. maps, magnetic tape, or magnetic disks). This can include offshore oil property maps, navigation charts, USGS quad maps, government lease maps, well inventory data on magnetic tape, shot line data, and sale/ lease data on magnetic tape. There is no limit to the amount and complexity of source information that can be entered, given a computer of sufficient storage capacity and processing capability. Maps may be of any size, at any scale, and in any projection.

As the data is assembled, it is entered in digital form into the data base. Each map or document is placed on an electronic digitizing table containing an electric grid that registers impulses from a hand-held cursor, as shown in Figure 2. using this cursor, the operator enters all necessary points which the computer records as individual X and Y coordinate values. At this stage, an accurate gobies can be established as a basis for all subsequent data.