Summary Excessive sand production, uneven recovery of reserves throughout the length of a horizontal well and early water and gas breakthrough are deemed to be the main problems while developing poorly consolidated terrigenous fields with contact reserves. Assessment of feseability of possible completion systems (gravel packing and autonomous inflow control devices were chosen for implementation) is necessary at the pilot stage of the project. Pilot wells shall be monitored at each stage including development, recovery, observation over the dynamics of water and gas breakthrough processes. The use of traditional PLT methods is not always technologically feasible and cost-effective. This article describes the experience of using stationary of intelligent inflow markers for permanent monitoring for the purposes mentioned above.

Well completion using technology enabling to improve performance and life time is an important objective in the development of PK1 productive reservoir of North Komsomolskoye field. The main challenge of the development of this productive horizon lies in the fact that the reservoir is shallow (1,120 m TVD) and consist of poorly consolidated sandstone, which results in massive production of solids during operation. In addition to that, proximity of GOC and WOC together with high oil viscosity in reservoir conditions results in early gas and water breakthroughs when using standard completion technology. Basic PK1 formation characteristics could be found in Table 1. Remote location of the field and impossibility to use all-year-round road transport of materials, equipment and personnel are additional operating problems which had to be resolved to ensure that the project is delivered successfully and without extra costs. Main questions which the project team had to deal with: What is the long-term solution to limit solids production at target drawdown to a level that would be safe for pumps and surface facilities?How to prevent early water and gas breakthroughs?How to drill a long horizontal section in poorly consolidate rock without any incidents knowing that previously several wells were lost in this zone due to well caving during drilling? To tackle these problems, we chose a completion technology for the open horizontal section using screens equipped with autonomous inflow control devices (AICD) and inflow tracers. To ensure sand control, we injected gravel packing in the annular space between the screens and the open well bore. In addition to that, we built a 1D rock mechanic model to calculate well bore stability. During the project execution we drilled 2 long horizontal sections without any incidents; tested completion technology with gravel packing (well A) and without gravel packing (well B); obtained the planned oil inflows; confirmed that the approaches adopted can be successfully used in the Full Field Development. Given all the particular features of the field and the well design, this operation can be rightly considered one of the most complex onshore operations that have been performed in the Russian Federation.

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