New Possibilities of Well Testing and Production Logging in Horizontal Wells with Non-Uniform Inflow Profile

Tuesday, 06 November 2018 Read 414 times
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  • Start Time: Tuesday, 06 November 2018, 19:00
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This paper discusses the integrated interpretation of PLT data collected in horizontal production (injection) wells with low flow rates and non-uniform inflow (injection) profiles. A factor analysis is performed and normativity of these methods in horizontal wells is defined.

 

Unlike vertical wells, production logging tool (PLT) techniques (even if adapted to specific conditions) turn to be inefficient in horizontal wells because of stratified flow in case of multiphase (water-oil-gas) fluid and the influence of wellbore trajectory features; this inefficiency is especially obvious in medium- and low-rate wells. It is believed that obtaining accurate and reliable phase profiles in a considerable number of horizontal wells using PLT techniques is very problematic.

Besides, it is only in rare occasions that one of the most important tasks of the PLT survey, which is finding the source of water inflow/breakthrough, can be solved in a horizontal oil well with non-uniform flow profile, even as a mater of quality. Keeping this in mind, gas breakthroughs due to significant negative throttle factor are more reliably identified both by non-stationary temperature logging records and a number of other well logging methods (e.g. SNL, spectral noise logging).

Under these conditions, efficiency of one of the main logging methods – well flow (spinner) measurement – becomes very low. However, alternative geophysical methods (first of all, temperature and water holdup logging) offer a number of additional opportunities. To implement them, the logging technology should include monitoring of well startup and drive change periods. To this end, the logging technology should be designed to allow a series of multi-temporal measurements during these periods.

The role of well testing is to diagnose the flow patterns that are not typical for a classical horizontal well model and estimated reservoir permeability.

Thus, in case of non-uniform low-rate inflow most of the useful information can be obtained by such methods as temperature logging, well testing and partly wellbore fluid analysis methods, which allows to:

  • diagnose phase structure of contrasting liquid and gas inflows based on dynamics of wellbore filling in time;
  • make assumptions on the flow rate of the predominant component based on the form, magnitude and character of temporal changes in behavior of temperature anomalies in intervals outside the working zones;
  • determine reservoir permeability based on well test results and information about the inflow profile.

Thus, a comprehensive interpretation of results of the above mentioned methods allows us to make quite an accurate assessment of the inflow profile and working zones of the reservoir. On the basis of this information we can optimize regimes of the well and reduce the water inflow and gas breakthrough risks.

 

Authors:

Melnikov Sergey Igorevich - Ph.D., Head of International Projects Support Department, Gazprom Neft Scientific and Technical Centre. He has been working in the STC since 2010, specializing in the tasks of integrated monitoring of field development. He supervised surveys on new projects of the Company, including in Eastern Siberia and offshore projects, as well as foreign assets. He is currently heading the department that provides geological support for the Company's foreign assets. In 2015, Sergey got PhD degree in Geophysics. He is the author of more than 30 papers.

Kremenetskiy Mihail Izrailevich. Higher Engineering Education (diploma with distinction) Russian State Oil and Gas University

Doctor of Engineering Science, Professor. Author of more than 170 papers, including monographs, patents for inventions, and two recently published books on the theory and practice of production logging and well-test. Works in the oil and gas industry since 1973, since 2000 research and analytical department specialist of the Sibneft company, since 2008 – expert LLC «GAZPROMNEFT SCIENCE & TECHNOLOGY CENTRE».

 

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