No abstract

The resource base of Western Siberia needs to be replenished to maintain the current development indicators. The reserves associated with the classic structural traps were diagnosed and mapped for the main horizons in Western Siberia. Replenishment of the resource base at the expense of such reserves is ineffective due to the fact that undiscovered traps of these types are thin, or lie at great depths, which ultimately negatively affects the quality of the resource base and the economic efficiency of their involvement in development. The driver of the growth and replenishment of the resource base under current conditions is the Achimov deposits, which are ubiquitous in this area at depths of 2500–3500 m and are genetically deep-water deposits of fans. The advantage of involving these deposits in development is often associated with the confinement to existing assets, where production is carried out from above and below-lying geological objects, the complexity is associated with the lithological type of traps, which is not diagnosed by direct analysis of seismic materials, as well as the extremely poor knowledge of the deposits over the area. Considering that the variability of properties over the area is a distinctive feature of Achimov deposits, the factor of poor knowledge by drilling significantly complicates the understanding of the potential of the deposits. In order to identify and assess the most promising areas for involvement in the development of the Achimov deposits, in PJSC Gazprom Neft the work “Regional assessment and zonal study of the prospects for oil and gas potential of the Achimov formation in the Western Siberia” was carried out. The goal and objectives is to form a reliable tool for searching and forecasting potential options using the generated regional maps of criteria (various characteristic properties and their combinations) built on the basis of data generalization throughout Western Siberia.

Nowadays demand makes gas one of the desirable hydrocarbon sources of energy. However reservoirs size and quality of new discoveries or old preserved one are poor. This fact set the task for simulation of accurate prediction in order to evaluate economic reasonability of production. This study concerns the question of changes gas production profile at the gas-bearing carbonate formation due to presence of transition zone. The different ways of simulation models initialization are implemented. Then the changes of the total output are compared and analyzed. In addition the advantages of initialization by means of J-function over capillary pressure curve assignment for the carbonate formation with highly heterogeneous flowing properties are explained. All results are coupled to vertical flow performance of wells which were matched at the tests. The study shows that transition zone should be taken into account in simulation modeling of the gas-bearing no less than for the oil-bearing formations. Also the total gas production compared with and without the transition zone implementation due to its production is sensitive to presence any liquid. Accurate J-function matching at the core data provide better result for water breakthrough thus the performance of wells and finally the total production profile. The vertical flow performance curves adjustment and subsequent use for the simulation is the additional need which considered because in the case of the surface equipment restriction, such as the tubing head pressure limits, the pressure loss in the presence of gas and water mixture could be huge which cause early shutdown of the wells. It is shown that gas bearing is not the reason to neglect the importance of the capillary force and the presence of the transition zone which has essential impact on the total formation performance.