October 14, 2012
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№ 9 (September 2012)

Prolonging Gas Production in Declining Fields

   Cenomanian gas fields in Western Siberia such as Medvezhje, Vyngapurovskoye, Urengoiskoye, Yamburgskoye, Komsomolskoye have been developed for over 30 years.

By Valery Minlikaev, Dmitry Dikamov, Alexei Kononov, Valery Gurjanov, Yuri Davydov, Vyacheslav Goncharov, Igor Smirnov, Jan Arents, Bob Okhuijsen

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   All of these fields are experiencing a signficant decline in production caused by decreases in reservoir pressure, well drowning, the use of antiquated field equipment, and physical wear. As a result, active discussions regarding gas extraction and complex utilization of low pressure field reservoirs are currently taking place. One way to optimize gas production in these fields is to utilize for distributed gas compression Mobile Compressor Units (MCUs).

   At the final stage of gas field development, reservoir pressure declines to a critical level. The rate of upward gas flow becomes insufficient to push reservoir fluid cleaner through compressor lift tubing. Fluid that gathers in the bottom hole tends to lead to automated shut down, making well operations difficult. Wells that are positioned in a cluster also intensify operating challenges. The different production capacity of each gas well in a particular cluster results in high cluster results in “high capacity” wells overdisplace “low capacity” wells.

   Reciprocating Compressor Stations control the operation of gas wells and gas extraction, but these stations are unable to regulate individual working conditions for each well. Installing MCUs in the gas extraction system can help solve these problems. Unit mobility and ease of installation of the compressor equipment allows for complete factory retiability. MCUs that are installed at the well head create individual conditions for each cluster well, providing the greatertemperature range and extending the life of the gas field.

   Under the cooperative framework agreement between Gazprom and Siemens, a Dutch division of Siemens - Siemens Niderland N. V. - developed a compression unit designed to increase the production life of a gas well (for Gazprom's department of gas and gas condensate production). Gazprom's Vyngapurovskoe field was chosen as a pilot project for the deployment of the Siemens Mobile Compressor Unit.

   The Siemens MCU can be transported by rail or by road.   The MCU includes a compact and reliable compressor module, electric motor, gas input and output manifold, lubrication system, closed loop water cooling system, power regulation system and electro-technical room with control panels and power transformers. All components included in the MCU are installed on the general steel platform.
The MCU is equipped with a screw-shaped oil-filled compressor that is reliable, features a low number of metal parts, and has small dimensions and a wide range of compression levels.. A flexible valve that is activated by hydraulic valves can be used to regulate operational capacity from 10-100 percent. The compressor drive component is powered by a  6 kW electric motor with a "direct" start.

   The Far North Region (Vyngapurovskoye field location) requires equipment containers to have electric heaters that ensure compressor equipment operability in negative outside temperatures. Ambient air electric heaters are switched on when container temperatures fall below +5 C.

   Applied container equipment arrangement system (three blocks – compressor, separator and water cooling system) features low mounting/demounting costs when unit relocation is needed. The Mobile unit MK-450 has been granted all necessary certificates and permits for application at Gazprom's gas-producing facilities.

   During the test period, operational parameters were controlled remotely from the Netherlands and outside temperature variations were within the range of +22 C to -50 C. The following technical parameters were analyzed: gas flow volume, pressure, temperature, lubrication oil level in the tank, vibration level, power supply voltage on each line, the main motor power etc.

In the pilot production period:
Approximately 60 million cu. m of natural gas was compressed using MK-450 unit.
Power consumption was from 297 kW/hour to 329 kW/hour.
Compressor running time amounted to 3,434 hours.
Wells tied to MK-450: #167, #176, #177, #179, #207, #208, #212 and #213.
Wells producing with the help of MK-450: #179, #207, #208, #212 and #213.
Inlet pressure was 0.38 MPa to 0.42 MPa.
Outlet pressure was 0.66 MPa to 0.77 MPa.

   Implementation of the MCU technology in the Vyngapurovskoe pilot project enabled production and gas extraction from previously shut-in wells #207 and #177. The MCU was able to create individual operating conditions for each well that was tied to the compressor unit.

   The MK-450 pilot project indicated that "distributed compressing" technology makes it possible to operate wells with low wellhead pressure, and that are not sufficient for normal gas extraction. The MK-450 increases production capacity and extends the life of the gas field.

   Siemens, Gazprom and Technogarant are presently working on this technology in order to prolong the service life of near-depleted gas fields.

   The compressor unit has been designed to function in fully automatic mode, offline control and in programmable logic controller-operated algorithms during emergency situations. Unit operation and centralized control is regulated at the main control panel at the Reciprocating Compressor Station. The unit is equipped with systems for remote monitoring of unit operational parameters. These systems are used for optimization of control algorithms and for accurate diagnostics to be made by the engineering center in the Netherlands in case of problems.

   Compressor units of this type are “minimally-manned technologies”. In other words, this is highly reliable equipment with automatic systems for production process control.This equipment requires no permanent presence of the maintenance staff. At present, Gazprom group is actively looking into the application of this equipment both at the gas fields under production and at those where development is planned.

   An Agreement on supply of MCU was concluded in February 2010 in Assen, the Netherlands, between Siemens Nederland N.V. and Technogarant, a leading Russian company on implementation of complex tasks for oil and gas industry. Technogarant conducted management and assisted in all project stages from signing of the Agreement to acceptance testing and equipment pilot operation which started in September 2011.

   General coordination of the project was performed by the specialists of the Department for gas and gas condensate (oil) production of Gazprom.

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