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The article describes new drilling methods recognized as testing works in the drilling company “Volkovgeologiya” JSC. A special feature of this method of drilling is the introduction of the airlift principle. The proposed technology differs in that it is applicable during well drilling and does not require investments for reconstruction, which is significantly reflected in the number of repair and restoration works. With a wide application of this method, the possibility of providing a huge economic effect in the operation of technological wells is described.

Karachaganak field is one of the largest accumulations of gas-condensate in the world. The field has been in production since 1985. Current development is focused on the oil rim and a gas injection programme has been implemented since 2004 using associated gas to support reservoir pressure. The internal architecture of the Carboniferous reservoir is complex. Following deposition of the Tula shale the reservoir is characterised by an initial development of aggrading mounds followed by a progradation phase. During the Serpuhkovian, a prograding clinoform boundstone geometry is the lateral equivalent of a shallow cyclic platform dominated by grainy sediments. A more confined steep sided pinnacle complex follows as the last stage of the carbonate platform evolution. Several environments of deposition are recognised in Karachaganak, including boundstone facies mainly deposited during the aggradation phase of the platform evolution, and the overlying cyclic platform. The target of the injectors wells is the cyclic platform, characterised by the deposition of tidal cycles which generally act as pressure baffle and lead to a high anisotropy in reservoir permeability. The paper focuses on the geological and dynamic review of the gas Injection with the aim of improving the knowledge on gas movement and the reservoir models/predictions, and of optimizing the field development.

Well spacing optimization is very important at the stage of drilling the reservoir. It is critical for the whole project economics. After the reservoir is already drilled it is very important to understand does existing wells drain all the reserves of infill drilling requires to improve recovery. Such task was solved on a tested area - Western part of Karachaganak gas condensate field. It has a complex geology, built as a massive heterogeneous carbonate reef of a Carboniferous age. PVT properties of the reservoir fluid significantly varies with depth. The area is produced with horizontal wells to maximize contact with the reservoir. The Multi-well Retrospective Testing (MRT) on base of multi-well deconvolution of historical rate and bottom-hole revealed well drainage area and well interference (1 – Aslanyan, 2018; 2 – Aslanyan 2017, 3 – Aslanyan 2019). The MRT study is showing a strong pressure depletion trend and a fair connection between wells in the certain areas like core of western build up.

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