Preparatory stage

Table of Contents

Preparation of technical design assignment

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Reliability and accuracy of initial data is a controlling factor in designing reliable gas processing scheme which is optimum in terms of capital and operation costs, and achievable result. Long term experience of operations with representatives from different industry segments has shown that customers often do not have clear view of required initial data scope for designing the gas cleaning systems. Actually, initial data have to be clarified and specified after commencement of design. Inevitably, it results in extension of design time and leads to additional costs for the customer. In many cases, the lack of reliable initial data is the cause of reduction in the quality of design and the project in general. By reason of this problem value, “Giprogazoochistka” OJSC has founded a special division for operation with the customer at the fist - pre-design - stage. The purpose of this division activity is to prepare technical design assignment and evaluate the entire scope of all investment costs for construction of gas cleaning system. Necessary measurements of gas stream parameters, expert inspection of existing equipment (in upgrading the facilities), computer generated simulations of gas cleaning system are carried out at this stage, as well as selection by the customer of gas cleaning system among the options proposed to him and differed by environmental and economic parameters.

List of works to be performed at the stage of technical assignment development for gas cleaning system:

1. Initial data acquisition, including methods of instrumental momnitoring

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1.1 Analysis of gas streams.

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Compositional analysis of gas mixture. Multipurpose gas chromatograph Agilent 3000 is used for these works. Since the device is portable, our specialists can install it directly at the customer’s unit. At present, the device configuration allows to perform measurements of all sulfur-containing gas components in the channels of sulfur recovery unit.

Versatility of device lies in its simple readjustment for analysis of other components in gas mixtures.

While analyzing gas mixture in conditions of industrial production, not only conventional precautions are to be taken but the change of sample shall be prevented during sampling process. It is particularly critical for sulfur recovery units: the gas containing hydrogen sulfide, sulfur dioxide, and water vapor together is extremely reactive. Our specialists possess required sampling methods that prevent loss of mixture compositional information.

The obtained data form a starting point for selecting gas cleaning method, designing the gas treatment facilities, optimization of operating modes for existing systems.

Gas mechanical impurities measurement. Correct measurement of gas mechanical impurities (solids and/or liquid drops) is the starting point for analysis of dust collection system. Adhering to sampling conditions is significantly important [1] in performing above measurements:

The company specialists own all required methods and skill to ensure correct measurements and results interpretation.

1.2 Expert evaluation of existing equipment, steel structures, foundations

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1.3 Performace forecasts for gas treatment units with due consideration of natural /associated petroleum gas field lifecycle.

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Lifecycle of natural/associated petroleum gas fields is characterized by commencement of reservoir exploitation phase, continuous extraction phase, and declining production phase. Formation pressure is decreased in line with this cycle. The above results in compositional change of extracted products, decrease in heavy hydrocarbons and light condensate ratio, water and hydrogen sulfide strengthening in gas, etc. Change in gas composition leads not only to redistribution of material flows of the plant units but to change in their operation conditions [2].

Generally, the producing organization plans a stagewise commissioning of different oil field areas (different horizons) to compensate for decline in output. This situation also shall be analyzed with regard to gas treatment and purification units.

Specialists from “Giprogazoochistka” OJSC perform forecasts of changes in gas parameters that are critical for gas cleaning units based on geological data and field development programs,  This data shall be referred to as initial data for further development and designing by optytions.

2. Study of gas cleaning schemes by options.

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Experience in design of gas treatment and cleaning units has proved - there are no two identical units existing. Very often several options conforming to environmental requirements of the Customer are assumed to be offered for processing the same gas.

For instance, the objective is to process acid gas containing 20% (vol.) of hydrogen sulfide  (the rest is CO2) and having hydrogen sulfide conversion rate into sulphur 97% minimum, and sulphur output amounting 30 thous.t/year. The following process solutions are able to provide these conditions:

Certainly, the results of above processes will be different. Therefore, the objective of gas cleaning system development at this stage is to make comparative analysis and select a process, which ensures design performance, fits the customer’s infrastructure in the best way, and has the best technical and economic performance.