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Fifty years after the first key well was drilled, Uvat oil remains the object of constant discussion. In the 1970s the industry's focus was on discovering major fields in the Khanty-Mansiysk region, while the promising fields of southern West Siberia were abandoned. It was only 10 years ago that independent subsoil users appeared in Tyumen Region and Uvat was revived. Among the Company's major projects, this is the one that may achieve a substantial production increment in the near future.

Sergey Samyshkin
(SUSamyshkin@tnk-bp.com),
Drilling Efficiency and Technical Limits Director,
Tyumen BU

Boris Zalogin
(BPZalogin@tnk-bp.com),
Drilling Technology Director, Tyumen BU

The Uvat project includes seven license areas (eight fields and 29 exploration targets) with more than 200 mln t of recoverable reserves (Fig. 1). Within the project framework it is planned to construct over 500 km of roads and 200 km of power lines.

The project also provides for construction of a strategic regional pipeline infrastructure over 300 km long that runs through an area of proven oil and gas presence that covers 30,000 sq. km in the southern part of West Siberia.

At the same time, developing the Uvat group of fields and constructing necessary infrastructure involves certain difficulties, the first issue being the logistics. The matter is that ground communication with the drilling pads is confined to only three months per year when winter roads are in place. The rest of the time it is possible to reach the fields only by helicopter or via the Demyanka River; however the navigation season is also short, lasting just one or two months when the river is up. That is why the major part of preparatory work, including delivery of drilling materials, must be completed during the short period when the winter roads are functioning.

As of October 1, 2008, 25 development wells have already been drilled at Ust-Tegusskoye field.

Advanced Solution: 48 Wells from a Single Well Pad
Following vigorous exploration and appraisal (E&A) activity in 2004-2007, the Uvat resource potential was estimated as exceeding 200 mln t (1.4 bln bbl) of recoverable reserves. Uvat is now entering a fundamentally new stage: the Company's best talents have been assigned to the project; an optimal development plan has been designed; E&A activity is underway; Urnenskoye, Ust-Tegusskoye, and Tyamkinskoye fields are being drilled out. The engineering aspect here is rather interesting: applying new well construction technology and state-of-the-art equipment makes it possible to drill up to 48 wells from a single well pad. Drilling extended reach wells that reach out to 3,000 m is not a technical limit for Uvat. The number of wells is determined by total oil flow rate restriction of no more than 4,000 tpd per site.
Fig. 2 Net Oil Map for Urnenskoye and Ust-Tegusskoye Fields

However such super well pads make it possible to simplify construction of utility networks for oil production and transfer to the processing facilities and reduce related expenses by 20 percent and more. The number of wells drilled from a single well pad is also restricted by the technical capability of the drilling rig including hook load capacity and nominal drilling depth, the drilling tool (drill pipes) specifications, application of additional equipment such as a top drive for the drilling string, as well as the geological structure of the field and possible hole problems.

In Uvat drilling is performed using five imported drilling rigs. The process involves a Russian drilling company and a drilling equipment maintenance team from an international service company. The team members work 24/7 as part of the drill crew, train their Russian colleagues, and monitor all operations. In order to prevent accidents, the drilling equipment restricted the tackle system speed during the first six months of work. But since drill crews have developed the right skills, tripping speed increased gradually.

Modeling for the Drilling Purposes
According to the resource estimate of the Uvat group of fields, the recoverable reserves of the Eastern Hub amount to approximately 95 mln t. If the current understanding of the reservoir geological structure is confirmed, the development plan will provide for drilling seven well pads at Urnenskoye field and 10 well pads at Ust-Tegusskoye field.

As of October 1, 2008, 35 development wells at Urnenskoye field and 25 wells at Ust-Tegusskoye field have already been drilled. The wells flow naturally at rates of 50 tpd to 200 tpd. Drilling has begun at Tyamkinskoye field in the Central Hub as well, where well *300 is also flowing naturally producing 50 tpd of dry crude oil. Reservoir geological models developed by Tyumen Petroleum Research Center (TNNC) are actively applied while drilling out the Eastern Hub fields (Fig. 2). Using models for the development drilling purposes helps minimize the risk of failing to penetrate the reservoir, as well as updating the pay distribution prediction.

Reservoir simulation models were developed based on the depositional environment analysis and 3D seismic and log interpretation; petrophysical functions were determined using core analysis. The structure and petrophysics of the models are constantly updated based on new geological and hydrodynamic reservoir data obtained during drilling and well testing.

Open-hole logging of new development wells is performed by specialists from Baker Hughes. They apply their own unique technologies including nuclear magnetic logging that make it possible to determine the reservoir properties of the bottomhole formation zone. The innovations are applied in development wells completion as well: the use of deeply penetrating perforation systems for underbalanced reservoir penetration makes it possible to minimize wellbore damage and complete a well with perfect penetration.

In Uvat drilling is performed using five imported drilling rigs and involves both Russian and international specialists.

One of the Uvat challenges is the remoteness of the fields.

Positive Outlook
The annual oil production in Uvat is expected to be approximately 2 mln t.
It is planned to reach peak production of 10.8 mln t in 2016 (Fig. 3). At present infrastructure is being constructed at Unrenskoye, UstTegusskoye, and Tyamkinskoye fields and facilities are being prepared for commissioning planned for the second quarter of 2009. In the near future the focus here will be on development drilling. At the same time, other Uvat fields will be prepared for commercial development. This includes E&A, design and permit documentation development, etc.

TNK-BP is the investor for the Uvat project with the Tyumen Region administration contributing to the financing of its first stage. Analysts forecast that these expenses will be paid off both in monetary terms and through a number of social benefits: Uvat development will fundamentally change the region's infrastructure, which will drive diverse industry growth and create over 8,000 new jobs. Thus, the Uvat project will largely contribute to the development of industry in the south of Tyumen Region.


Fig. 3 Uvat Oil Production Profile

Interesting Information:
About half of Uvat's recoverable resources (95 mln t / 300 mln bbl) belong to the Eastern Hub. It includes two major fields: Urnenskoye (discovered in the 1970s) and Ust-Tegusskoye (discovered in the 1990s). Malyk field with approximately 3 mln t of recoverable reserves was discovered in 2006 to the east of Ust-Tegusskoye field by exploration well *5. In 2008 the E&A program resulted in discovery of Zapadno-Epasskoye field with approximately 2.5 mln t of recoverable reserves.

The Central Hub also includes two major fields: Tyamkinskoye (discovered in 2004) and Tamarginskoye (discovered in 2006).

The E&A activity performed in 2006 and 2007 confirmed that this area has significant resource potential exceeding 100 mln t (750 mln bbl).

As of the end of 2007 the proven and probable reserves amounted to 25 mln t (187 mln bbl).
The Central Hub extensions include smaller fields in the Northern Hub as well as the Southern Hub that has yet to be explored. Here E&A drilling and 2D and 3D seismic surveys are being performed in order to confirm the area’s resource potential, which is expected to amount
to 60 mln t (450 mln bbl).

Labels: oil gas, Russia, TNK BP, Tyumen, Uvat

posted by The Rogtec Team @ 16:52 

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