The article describes the choosing a water-and-gas shutoff technology in horizontal wells (HW) drilled in terrigenous reservoirs of the North Komsomolskoye field. The well completion system is characterized by the use of liners equipped with external liner packers and inflow control devices (ICD). To solve the problem, the world experience in the use the water-and-gas shutoff technologies in HW was studied. A matrix for choosing a technology with the use of technical means and combined effect was developed based on the type of isolated fluid, the type of reservoir and the method of well completion. The technology of installing a straddle system with cup packers and a blind inter-packer pipe in a horizontal wellbore was selected to increase the success of work on isolating the inflow of water and gas in difficult geological conditions of the North Komsomolskoye field. The technology was successfully tested: a producing well with almost 100% water cut was return to effective production. A similar straddle system, but with a perforated spacer pipe, was used for directional injection of sealants selected for the conditions of the North Komsomolskoye field into the water cut zone of the horizontal wellbore. The results of pilot field tests indicate that there is a prospect of using water-and-gas shutoff technologies to limit water and gas inflow at the North Komsomolskoye field.

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The complex interbedded heterogeneous reservoirs of the Severo-Komsomolskoye field are developed by horizontal wells in which, as part of the pilot project's scope, autonomous inflow control devices (AICD) are installed to prevent early coning and gas breakthroughs in long horizontal sections and reduce sand production, which is a problem aggravated by an extremely low mechanical strength of the terrigenous deposits occurring in the Pokur formation of the Cenomanian stage in this area. The zones produced through AICDs are separated by swell packers. The issue of AICD effectiveness is discussed in the publications by Solovyev (2019), Shestov (2015), Byakov (2019) and some others. One of the methods used for monitoring horizontal sections with AICDs is production logging (PLT). However, due to the complexity of logging objectives, the use of conventional logging techniques makes the PLT unfeasible, considering the costs of preparing and carrying out the downhole operations. This paper provides some case studies of the Through-Barrier Diagnostics application, including passive spectral acoustics (spectral acoustic logging) and thermohydrodynamic modelling for the purpose of effective estimation of reservoir flows behind the liner with AICDs installed and well integrity diagnostics. As a result of the performed diagnostics, the well completion strategy was updated and optimised according to the log interpretation results, and one well intervention involving a cement squeeze with a straddle-packer assembly was carried out.

Most of the new oil fields in Western Siberia have unfavorable conditions for field development such as excessive gas cap presents, oil rims and active water aquifer. The North-Komsomolskoe oilfield is also characterized by poor consolidated sandstone and high viscous oil. Different types of reservoir completion (ICD, ACID, AICV) have been decided to trial test for this field in order to mitigate early water or gas breakthrough along the long horizontal well. During this trial testing of the optimum type of lower completion, the continuous well monitoring is required; clean-up efficiency estimation after drilling, quantitative estimation of inflow per compartment along the wellbore and localization of water or gas breakthrough. Traditional well logging methods like production logging cannot always be easily applied technically and be cost-effective for many surveys during well life. This article presents the result of using a novel technology based on chemical tracer for continuous well monitoring. Polymer matrix with chemical markers for oil and water have been integrated into different types of lower completion (ICD, AICD, Stand Along Screen) and run into the hole as a part of liner string. Technology of intelligent chemical tracers is used to monitor well performance over a long period of well life, which allows to obtain the following information: effectiveness of clean up operation after drilling, inflow per compartment and water/gas breakthrough localization zone. To confirm interpretation results based on chemical tracer, the traditional method (production logging) was used to measure inflow along the wellbore and compare with result from tracer survey.