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Oil and Gas Eurasia: High Technologies for Sakhalin-II Offshore Facilities

By Oleg Karpushin

For a number of reasons, the Sakhalin-II project run by the Sakhalin Energy company is unparalleled in its scale.

First, it is being implemented in severe climatic conditions in the Sea of Okhotsk where the water is covered with thick ice for six winter months. Secondly, all operations  have to be carried out with the fragile northern nature of Sakhalin Island in mind. Thirdly, the area is prone to high seismic loads. In addition, Sakhalin-II is unique in its scale and integrated project as hydrocarbon production, transport and processing taking place hundreds of kilometers away, will be monitored from a single control center. In response to these dramatic challenges, Sakhalin Energy could not help but rely on state-of-the-art technologies, or in some instances even pioneer their application.

For example, the currently operating Molikpaq (PA-A) oil production platform introduced a zero flaring system in 2005 to eliminate flaring of associated gas, which has both financial  and environmental. Today, all associated gas is injected back into the reservoir using gas compressors. Consequently, the gas will be supplied to a manifold whose construction is nearing completion.

In addition, a zero waste discharge program has been implemented, whereby all process fluids, effluents, and produced  water can be re-injected back into a discharge well. Similar systems will be commissioned at Piltun-Astokhskoye (PA-B) and Lunskoye-A (LUN-A) offshore platforms to prevent even the smallest spill from getting into the Sea of Okhotsk, either in the course of drilling or during the platforms operation.

Besides, the platforms are unique in their own right. For the first time in Russia, they are placed atop the concrete gravity base structure (CGBS) capable of withstanding heavy seismic and ice impacts. Traditionally, base caissons have been preferred although they are good for shallow waters only, while the sea depth around Piltun area is 32 meters and at Lunskoye field it reaches 48 meters.

The towing and installation of the LUN-A (weighing 21,800 tons) and PA-B (weighing 28,000 tons) topsides  onto their final resting place on top of the CGBS have broken world records for installation operations of this type.

Considering the potential seismic risks of the field development area, the topsides have been mated to the four legs of the concrete gravity base using sliding connections called friction pendulum bearings installed at the top of each leg. This method has been used for the first time ever in Russia and worldwide, as such gigantic bearings cannot be found elsewhere in the oil and gas industry.

Sakhalin Energy contracted a team of researchers from Earthquake Protection System Company to carry out a big research project. They built up a special bench allowing the in-situ testing of bearings to be performed for the project. According to calculations, these pendulum dampers will work through the entire service life of the platforms, which can help protect the topside against damage during a severe earthquake that occurs once in 3,000 years.

Naturally, it takes more than just calculations. All platforms will have their seismic monitoring systems as there is ongoing checking of the condition of the gravity base structures, as well as on-going monitoring of seismic loads’  etc.

Due to integration of many elements of Sakhalin-II  project, Sakhalin Energy has focused on automation of every process, starting from the drilling operations to the management of the various assets.

Nobody will be too surprised by the well path control systems available in Russia, as they have been used on a regular basis. But one of the systems to be built at the Piltun field is set to become a unique one indeed. The well in question will penetrate the formation from  under the reservoir , thus making a loop under the ground This will require both specialist drilling equipment and proper skills from those who will steer it.

Here, the word “steering” is not used accidentally. The PA-B platform, which is purpose-designed for full automation, is undergoing commissioning and hookup work now. Every process, which traditionally involved drilling crews is now mechanized and automated in full. The need for personnel attendance on the drilling derrick is eliminated with the  supervision of the drilling operations being provided via joy sticks from the drill operator’s control room.

The situation will remain the same in the production operation stage, too. For instance, the reservoir pressure at the Piltun field will be maintained through so-called “smart wells”. Water should be injected into wells at various intervals (up to five of them) with packer separation. Each interval will have its own injection mode.

A reservoir engineer sitting in his office in Yuzhno- Sakhalinsk will be getting real-time data from the platform reading the pressure, temperature, and other para-meters available within each interval. The field development model will be updated online on a permanent basis. By sending appropriate command to the platform, the engineer will be able to rapidly modify the water injection parameters, thus increasing the reservoir’s productive capacity. All this will be done without human intervention at the platform.

As it was already stressed, the Sakhalin-II project is a highly integrated one. That is why a malfunction in just one part, for example, at the LNG plant will immediately result in appropriate reaction on the platforms offshore.

Technologies of full-automatic control over the oil and gas production process allow the platform crews to be kept to the minimum, thus reducing overall safety risks. For example, LUN-A gas producing platform will have only a day shift for drilling. Overnight, the platform is going to be operated from the Onshore Process Facility, i.e. from shore.

Innovation technologies utilized by Sakhalin Energy will help ensure efficient and safe production process, while the experience,  gained from construction and operation of these complex facilities, will undoubtedly come handy during implementation of other projects aimed at development of the Russian shelf under severe conditions of Arctic seas.

http://www.oilandgaseurasia.com/articles/p/40/article/391/

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