Abstract

Field production monitoring problems in Russia are not related only to procedures; they also concern managerial issues. Usually there is no special department within an oil company that would interpret the well-test and production-logging results for their further use for production enhancement. "Sibneft" company is a rare exception where the results of all surveys are processed and interpreted in a specific department which constitutes a part of the company's structure and controls the well testing and production logging activities. The problems related to the well testing and production logging techniques are basically due to difficulties inherent to the production of residual reserves. Conventional well testing and PLT methods are poorly conclusive when applied in reservoirs with low permeabilities and poor producers with high watercuts. Sibneft implements therefore the welltest procedures that involve long swabbing stage followed by downhole well shut-in as well as long lasting welltests using memory remote control gauges including pressure gauges run into the well at the pump inlet. Stand-alone gauges such as pressure, temperature, spinners and watercut gauges are used for monitoring commingled production. Global technology for permeability adjustment based on logging, well testing, production logging and production data was worked out in Sibneft. Thus, 3D permeability cubes were generated for the most of the reservoirs and matched to the well-testing history; the relative distributions of flow properties being derived from log data. Problem of monitoring of the flow composition in the wells producing multiphase liquids and especially the horizontal wells is still poorly solved in Russia.

Introduction

Integrated studies of productive reservoirs and wells using such direct methods as logging, well testing and physico-chemical analyses constitute an integral part of information support for oil and gas field development systems. The acquired data on reservoir properties, their current oil and gas saturations, depletion character, water flooding efficiency, well performance failures and so on allow timely development scheme adjustments and optimization both for the entire field and individual targets. When properly set up, the field development control may become a reliable information basis for field development planning. The information support system of all the FDP stages should include integrated production logging, well testing and well services.

Organization of well logging and testing

Organizational problems which are typical for Russia are to the fact that production companies have no in the organizational chart a single unit responsible for well logging and testing, interpretation of results and integrated implementation of the obtained results in the field development systems. The authors have extensive experience in reviewing well log and test materials concerning oil fields in Russia and must note their poor standards by and large. Individual companies ignored Federal regulatory requirements and suspended for 2 or 3 years any well surveys aimed at development control and reservoir property refinement. When assessing new assets put on tenders one has to rest content with little or no good well tests and logs which makes it difficult to forecast oil production for the future. Nevertheless, certain Russian companies maintain yet a satisfactory level of production logging as a means of development control. Sibneft company stands out from those companies. Effective measures are taken in all the Sibneft fields to run formation tests and implement a continuous development control program. A development control team was therefore set up recently in the company (fig. 1). Their purpose is to complete the existing servicing units and interpretation departments with analytical groups dealing in classification, analysis and application of the well testing and logging results in field development planning and monitoring stages. The Sibneft management and now the leading research Analytical Centre coordinates the activities of all the well testing and logging groups based both in production regions and in corporate research and analytical centers.

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