The Vikulov formation in the Tyumen District of southwestern Siberia consists of incised-valley deposits and shallow-marine delta-front sands, which form oil reservoirs in the area of the Krasnoleninsk dome. Reservoir quality varies considerably depending on the depositional facies. In places, high permeability channels and bars were deposited, whereas the more distal sands have much lower permeability and must be fracture stimulated to produce economically. To compound the situation, the Vikulov sands are in the transition zone, and in many places, wet sands are in close proximity to the oil-productive sands. For this reason, many of the initial completions within the acreage had poor results.
To improve field performance, a multi-disciplinary team was assembled. The team consisted of a geologist, petrophysicist, completion, production and reservoir engineers, facilities personnel and service company engineers. Their task was to better understand the properties of the Vikulov and the reservoir, determine well locations with maximum production potential, optimize stimulation treatments and provide infrastructure to produce the oil.
This paper will review the initial completion efforts and explain the methodology and changes implemented by the team to describe and define the reservoir, modify stimulation methods using a grid-based, non-coupled fracture simulator and optimize well productivity. Production increases in excess of five fold have been realized for many wells.
East Kamennoye Overview
The East Kamennoye field is located approximately 100 kilometers northwest of the city of Khanty Mansiysk and covers 876 sq km (see figure 1). Since its discovery in 1962, more than 200 wells have been drilled on the East Kamennoye license.
East Kamennoye produces from both Cretaceous and Jurassic formations, but the majority of the production and reserves is currently from the shallow Cretaceous Vikulov reservoir. The field is part of a much larger hydrocarbon accumulation which also includes the West Kamennoye license area. The Vikulov formation consists of normally pressured, low to medium permeability sandstones with a low gas-to-oil ratio. The producing wells require artificial lift. Standard completion consists of fracture stimulation followed by installation of submersible or beam pumps. Water injection has been initiated in the Vikulov and an early response is noted. Vikulov oil production for the month of May, 2006, averaged just over 22,000 bpd.
Geology
East Kamennoye consists of a number of independent producing formations (see figure 2). These include the shallower Cretaceous Vikulov (VK) reservoir encountered at 1,420 to 1,465 meters that contains the majority of the proved reserves, the deeper Jurassic reservoirs (Abalak, Tyumen and Sherkalin) at depths between 2,350 and 2,600 meters, and the underlying weathered and fractured Paleozoic Basement.
