Categorization and Auditing of Reserve Estimates in a Series of Kazakhstan Oil and Gas Fields, Including a Probabilistic Analysis
Authors: Lencioni L.C. , Johnston B.G. , Hagemann S.G. 
Published: December 2007

Many western oil and gas companies are evaluating opportunities for projects in the Former Soviet Union (FSU). The type and quality of available data, as well as existing interpretations made by the Soviets, are often very unfamiliar to engineers without experience in the FSU. This paper presents a case study of an audit of reserve estimates for a series of eight undeveloped gas-condensate and volatile oil reservoirs, the Kamen/Tokarev-Teplov (KTT) Trend, located in northwestern Kazakhstan.

The study described in this paper was commissioned by the International Finance Corporation (IFC) to evaluate the provision of financing and taking an equity in the project. Thus, the concerns of the IFC involved several questions:What are the reserves upon which financing can be based with relatively low risk?What are the most likely reserves which should be considered for longer term planning and budgeting purposes? andWhat are the upside potential and downside risk?

These questions can be effectively answered concurrently by the use of a probabilistic reserve analysis.

The data review for these fields yielded the results that the majority of the available data was of good quality and reasonable and sufficient to use in estimating reserves. Some of the well test and PVT data, however, showed inconsistencies due to measurement or sampling techniques which had to be resolved. Adjustments were made to account for these data problems.

This paper presents a discussion of our review of the data and previous interpretations and reserve estimates, and a description of our deterministic reserve estimates and probabilistic analysis.

Introduction

Eight partially to wholly delineated gas, condensate, and oil fields located in the northwestern Peri-Caspian Basin of Kazakhstan have been designated the Kamen/Tokarev-Teplov (KTT) Trend (Fig. 1). The fields were mostly discovered in the early 1970s. They are capable of production from Lower Permian reefal carbonate reservoirs in subsalt (and intrasalt) structural closures, in subsalt Permian reefal carbonates that are porous and fractured. The Stepnoi Leopard Ltd., Joint Venture signed an agreement with the government of Kazakhstan in 1995 to develop the discovered, but non-producing hydrocarbon reserves of these fields. The partners in this JV are Snow Leopard Resources, a private Canadian oil and gas exploration and development company, and two Kazakh state companies.

Approximately 114 wells have been drilled in the KTT Trend (many have been logged and tested), and extensive seismic surveys have been acquired and interpreted. The eastern fields, Teplov, West Teplov, East Gremyachin and Gremyachin are capable of producing gas, condensate, and oil. The four western fields, Ulyanov, Tsyganov, Tokarev and Kamen are gas/condensate-productive (Fig. 2). Under Snow Leopard's operational control, the JV intends to re-enter and retest a number of these wells that were temporarily abandoned, and drilling of new wells is also contemplated in the early phases of development. The first stages of the reentry program will begin with Well Teplov 74, followed by Teplov 72. These wells will be extensively tested to provide performance and fluid data to be used in design of the central processing facility. For Teplov 74, the rig site has been prepared and local services contracted. Initial results will likely be available this fall.

Development is scheduled in a phased approach with Phase I of the project designed to produce 2 million cubic meters per day of gas and 1600 cubic meters per day of liquids from nine wells. P. 607