Summary
Ever since its discovery in 1977, the Loma La Lata field, located in the
Neuquén basin, has been considered one of the most important gas fields in
South America.
During the last decade, the progressive reduction in the reservoir pressure
has led to successive changes in the field’s operation conditions: from high to
medium pressure, and, most recently, to low pressure.
As the reservoir pressure depletes, the subsequent reductions in the gas
velocities bring about changes in the flow regimes and increasing liquid flow
rates. These liquids produced at the wellbore and/or generated by vapor
condensation through the production string contribute to increase the pressure
drop along the tubing as well as the flowing bottomhole pressure, and will
eventually reduce or prevent production.
In most cases, not only does liquid loading arise as a consequence of these
changes in operation conditions, but also other production problems, such as
mineral scales and organic deposits, and the difficulty to implement corrosion
prevention conventional batch treatment programs aimed at extending the life of
the production strings.
In addition to these factors, the increasing hydrocarbon demand, Argentina’s
energy policy, and economic restrictions are also matters of relevance when it
comes to implementing conventional solutions that imply several shutdown hours
per treated well.
The aforementioned problems have encouraged the operating and services
companies to search for technological alternatives providing not only technical
solutions but also economical benefits.
After 1 year since a novel capillary string system that allows for the
injection of chemical products, and/or the deployment of special devices such
as memory gauges at the desired depth was introduced in the country, the
results obtained in several tests show a very promising future.
This paper summarizes the first-year results achieved using the capillary
string technology as a tool for production enhancement and optimization in the
Loma La Lata field.
Introduction
With 196 major wells and an average daily production of 25 million standard
cubic meters (883 million standard cubic feet), Loma La Lata is the largest
producing gas field in South America. This field, located in the Neuquén Basin
in the Neuquén Province of Argentina, was discovered by the formerly
state-owned oil company YPF in 1977 and is currently operated by private
Repsol-YPF under a concession that will last until 2027.
The area covered by the main gas fields in the Neuquén basin includes
4,481.47 Km2 that are operated and 2,922.20 Km2
non-operated. Within this area, the Loma La Lata, Sierra Barrosa, Aguada
Pichana, and Aguada San Roque fields supply approximately 31% of the
Argentinean market total gas demand. Additionally, these fields provide for
approximately 23% of the Argentinean natural gas exports, 59% of the industrial
delivery, and 62% of the distributing companies gas supply.
At the beginning of their exploitation, the wells in the Loma La Lata field
produced at a high pressure oscillating between 90 and 100 kilograms per square
centimeter. Given the fact that trunk gas transportation pipelines operate at a
pressure of 70 Kg/cm2 (6.86×106 Pa), it was imperative then to
reduce its pressure before the gas was injected into these pipelines.
As time went by, the reservoir pressure started to gradually decline as a
natural consequence of its exploitation. At present, approximately 60% of the
total gas flow rate is produced at medium pressure, between 40 and 70
Kg/cm2 (between 3.92 and 6.86×106 Pa), and the remaining 40% at low
pressure, between 15 and 40 Kg/cm2 (between 1.47 and 3.92×106 Pa).
The estimations indicate that by 2007 the whole field will be producing at low
pressure.
As the power demand is increasing, the operating company has on the one hand
started to invest in compressors in several plants in order to inject the gas
into the pipelines at the specified pressure and, on the other hand, to
investigate possible methods to resort to when the pressure becomes lower than
15 Kg/cm2 (1.47×106 Pa).
The first stage of a major gas compression project began approximately 6
years ago. During the last 4 years, a second stage has been initiated, and the
third phase will be finished by 2007. By then, Repsol-YPF will have installed
67 compressors in the field, including new and reformed ones.
© 2008. Society of Petroleum Engineers
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History
- Original manuscript received:
29 January 2007
- Meeting paper published:
15 April 2007
- Revised manuscript received:
6 August 2007
- Manuscript approved:
30 August 2007
- Version of record:
15 August 2008
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