Offshore Facilities Weight, Area, and Cost Estimation Performed by Systems Computer Simulation
Authors: Smith R.S. , King R.D. , Talley D.L. 
Published: October 2008

A computer program has been developed to simulate the total facilities, substructure, weight, area and cost parameters of offshore oil and gas production platforms. This program was developed as a Joint Industry Project with 19 major oil companies. The program will perform the following activities from approximately 2.50 'Management Decisions'.automatic heat and material balances for offshore production facilities including a specified crude vapor pressure product and gas lift recycleutility balancesphysical sizing of all major equipmentdry and operating weights of all major equipmentdry and operating weights of all bulks by category (including pipe, valves, fittings, local instrumentation, electrical items, equipment support steel, pipe supports, insulation and painting)weight and area estimate for 6 different substructures (fixed and floating types)installed cost estimate for the complete production related facility and substructure.

This program, which was developed for feasibility study applications to field developments, is the natural progression of a systems approach to estimating the weight and area impact of important management decisions. The data collected to provide input for the systems came from historical installed parameters, extensive study work with bulks, and supplier information.

The computer program and its data base are viewed as important economic study tools to rapidly review the relative impact of basic design decisions. Very often design decisions for oil or gas field development are based upon limited information and can prove costly to rectify.

With the use of this program, envelopes of field development parameters may be rapidly developed with parametric cases to provide - management with better information for their design decisions.

Examples of the results of the program will be presented, which relate the impact of various elemental management decisions.

Introduction

The latitude of production variables and system requirements for offshore facilities is wide. Often production platform cost estimates for feasibility studies cannot rely upon past historical information. Because initial information may be sparse, many assumptions have to be made and large contingencies may be added to the development costs.

To reduce the magnitude of the cost contingencies, a computer simulation of an offshore production facility has been developed to perform economic estimates based upon detailed scoping of equipment and weight analysis. The first general 'combined services platform' program was developed as a Joint Industry Project with 19 major oil companies. Other programs have been completed and are under development for more specific processing needs.

Figure 1 illustrates the linear flow of information from the input 'Management Decisions' to the process simulator and related systems routines. The program will perform a process simulation of the production facilities, size all of the required equipment, estimate the dry and operating weight of all major equipment and bulks, and perform a cost estimate for the topside facilities and supporting substructure.

The basic premise of this approach is that accurate scoping and sizing of major equipment is the key to good offshore weight, space, and cost estimates. The method uses a pyramid-type systems approach in which every item of equipment is accounted for and grouped into several systems fully describing the facilities.