Systems for collecting and preparation of oil and gas and criteria for their selection (PDF)

The production of oil is a complex technological procedure consisting of several equally important segments. One of the most important phases is the collection and preparation of oil, which affects the process of production from technical as well as from economical aspects. The choice and method of designing systems for oil collection and preparation is a very complex task that depends on the number of concrete parameters; this carries with it, above all, the difficulty in finding technology that will enable optimal work of wells as well as finding the continually and quality functioning of the entire production process. It is important to mention that each well is a case in itself; there are no broad or typical solutions for oil collection and preparation. Each production project on a field is involves individual solutions dependent upon situation-specific conditions.
The most important factors in finding the best solutions are experience and knowledge of problem-solving methods in similar fields worldwide. As this is the case, this thesis is based on analysis of a selection of different fields from around the worlds that, combined, represent one system of oil collection and preparation and should satisfy even the strictest criteria.
The task is:
At oil-gas field (X), 27 wells are drilled and prepared in the development phase for oil and gas production. The average production of peripheral wells involves around 20 m3/24h of oil, 10 m3/24h water, 800 m3 s/24h gas; while central wells involve the production of 35 m3/24h oil 1000 m3 s/24h of gas. Pressure at the well head of the well is 30 [bar], and the temperature is 30° C. The shape of the field and layout of wells are shown in diagram (1). The following are needed to define the design: 1) optimal scheme for collection of production fluids, 2) optimal technological scheme for collective station with basic elements, 3) basic parameters of all elements for collective station.
When defining the collection scheme, it is necessary to take in account the number of wells, geographic layout of the wells, technical and economical functionality of the chosen scheme of collection etc. In defining the scheme of the collective station, it is necessary to design technology that enables the collection of produced fluids and their separation as well as the preparation of further transport, disposing of and sending the water without endangering the human environment etc. Additionally, the technology of the collective station must ensure the continuous monitoring of elements of station as well as each well in order to observe well behaviour and adjust regimes of production according to conditions in wells.
When assembling a collective station, it is necessary to design equipment that enables functionality of the station. That means designing measuring separators, dehydrators, reservoirs for hydration and storage, systems for collecting and measuring the gas, and onward transport, etc.