The peculiarity of oil-gas-condensate fields development

UDK: 622.276.012
Key words: scheme of arrangement, gas-liquid ratio (GLR), gushing method of extraction, oil and gas field
Authors: K.I. Povyshev, A.S. Koptelov (Gazprom Neft NTC LLC, RF, Saint-Petersburg

The main feature of the development and operation of oil-gas-condensate fields is the extraction of oil from oil rims with subsequent extraction of gas, this situation requires a special approach to the construction of infrastructure to ensure maximum economic benefit and ensure safe operation. Significant differences in physical and chemical properties of oil and gas (viscosity, density, compressibility) lead to very different approaches to the formation of a system of collection and preparation of crude production to oil and gas fields. The typical scheme of oil field development is characterized by: artificial oil lift with a short water-free production period or its absence; pressure in oil gathering system up to 4.0 MPa; collector and collection system; technological processes of oil processing (separation, dehydration, desalting, and oil stabilization). The typical scheme of arrangement of natural gas fields is characterized by: free-flow production method; pressure in gas gathering system of 6.0 MPa or more; radial or mixed collection system; technological processes of gas treatment: (separation, dewatering water, separation of heavy hydrocarbons (C3+), condensate preparation and stabilization).

Thus, when designing a gathering and treatment system for oil-gas-condensate fields the task is to combine oil and gas production processes while ensuring safety and economic efficiency.

Yaro-Yakhinskoye oil-gas-condensate field is located in the North-Eastern part of Purovsky district of Yamalo-Nenetskiy autonomous region. Recoverable reserves in categories C1 and C2 exceed 225 million tons of oil and 415 billion m3 of gas. Main development objects layers BT represent oil-gas-condensate deposits with a massive gas cap and underlying water, oil-saturated thicknesses range from 3 to 11 m and are characterized by a high degree of vertical heterogeneity and weak vertical anisotropy. The saturation pressure is equal to formation pressure (30.6-33.5 MPa). The gas factor varies from 195 to 206 m3/m3, while production is complicated by the presence of gas breakthrough gas cap, the contents of which at the mouth can reach up to 5000 m3/m3.

According to the results of feasibility calculation of variants of the Yaro-Yakhinskoye field arrangement we can draw the following conclusions. The most economically viable and technically safe is a variant of the two-pipe system for gathering well production: low pressure (up to 4.0 MPa up to gas breakthrough gas cap to the producing wells) and high pressure (up to 10.0 MPa after gas breakthrough gas cap to the producing wells). The economic effect is achieved due to the design of the target bottomhole pressures, and as a result, the production profiles of oil and gas. The proposed solution provides the flexibility and reliability of the collection system, the entire period of operation of the field.

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