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Experience and analysis of the results of drilling wells with extended horizontal shafts in the Upper Jurassic sediments of Western Siberia

UDK: 622.243.24
DOI: 10.24887/0028-2448-2019-8-36-39
Key words: Upper Jurassic deposits, horizontal wells, rock cuttings, geosteering, drilling
Authors: V.D. Nemova (LUKOIL-Engineering LLC, RF, Moscow), G.A. Usachev (LUKOIL-Engineering LLC, RF, Moscow

The article describes the successful experience of geosteering while drilling wells with a long horizontal completion in the Upper Jurassic deposits. The article deals with the issues of geology of the object, the structure of the section of the target sediments, also example of reservoirs discrimination is given. Reservoirs in the section of the Upper Jurassic sediments are interlayers 0.5–3.0 m thick, which can be clearly distinguished according to geophysical studies of wells and cores. A well test field experiment conducted to substantiate the position of the reservoirs in the section is described. The choice of the target interval for drilling long horizontal boreholes in order to maintain the stability of the wellbore and obtain maximum oil inflows is validated. The goal was to support the drilling of horizontal shafts in the target interval of Upper Jurassic sediments with a thickness of 3-5 m. In the conditions of the impossibility of attracting high-tech logging complex for horizontal shafts, a method of geosteering in Upper Jurassic deposits using GR and rock cuttings during the drilling process has been developed. The high degree of characterization of the Upper Jurassic deposits by the data of core studies made it possible to identify indicator elements, the changes of which are most contrasting in different interlayers. Based on the analysis of drilling results, a series of conclusions was made. The proposed technique was tested in the process of drilling 9500 m of horizontal shafts and its high information content and reliability was confirmed. This technology is not expensive and can be implemented on any field after equipping the station for geotechnical well testing with portable devices for determining the elemental composition of rocks. To replicate this technology to other fields, it is necessary to study the reference sections of target sediments from the point of view of layer-by-layer changes in the elemental composition of rocks.

References

1. Panchenko I.V., Nemova V.D., Smirnova M.E. et al., Stratification and detailed correlation of Bazhenov horizon in the central part of the Western Siberia according to lithological and paleontological core analysis and well logging (In Russ.), Geologiya nefti i gaza, 2016, no. 6, pp. 22–34. В В В В В В В 

2. Slavkin V.S., Alekseev A.D., Koloskov V.N., Some aspects of a geological structure and prospects of oil-bearing capacity of Bazhenovskaya suite in the West of latitudinal Priobye (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2007, no. 8, pp. 100–104.

3. Nemova V.D., Gavrilov S.S., Issledovaniya kerna otlozheniy bazhenovskogo gorizonta, kak osnova dlya interpretatsii dannykh seysmorazvedki (Research core of deposits of Bazhenov horizon, as the basis for the interpretation of seismic data), Collected papers “Petrofizika slozhnykh kollektorov: problemy i perspektivy 2014” (Petrophysics of complex reservoirs: problems and prospects for 2014), Moscow: Publ. of EAGE Geomodel', 2014, pp. 212–230, ISBN 978-94-6282-030-2.

4. Nemova V.D., Panchenko I.V., Localization of inflow intervals and storage volume of the Bazhenov formation, Sredne-Nazym oil field (In Russ.), Neftegazovaya geologiya. Teoriya i praktika, 2017, V. 12, no. 1, URL: http://www.ngtp.ru/ rub/4/11_2017.pdf

5. Nemova V.D., Panchenko I.V., The productivity factors of Bazhenov formation in Frolov megadepression (Western Siberia) (In Russ.), Neftegazovaya geologiya. Teoriya i praktika, 2017, V. 12, no. 4, URL: http://www.ngtp.ru/rub/ 4/46_2017.pdf

The article describes the successful experience of geosteering while drilling wells with a long horizontal completion in the Upper Jurassic deposits. The article deals with the issues of geology of the object, the structure of the section of the target sediments, also example of reservoirs discrimination is given. Reservoirs in the section of the Upper Jurassic sediments are interlayers 0.5–3.0 m thick, which can be clearly distinguished according to geophysical studies of wells and cores. A well test field experiment conducted to substantiate the position of the reservoirs in the section is described. The choice of the target interval for drilling long horizontal boreholes in order to maintain the stability of the wellbore and obtain maximum oil inflows is validated. The goal was to support the drilling of horizontal shafts in the target interval of Upper Jurassic sediments with a thickness of 3-5 m. In the conditions of the impossibility of attracting high-tech logging complex for horizontal shafts, a method of geosteering in Upper Jurassic deposits using GR and rock cuttings during the drilling process has been developed. The high degree of characterization of the Upper Jurassic deposits by the data of core studies made it possible to identify indicator elements, the changes of which are most contrasting in different interlayers. Based on the analysis of drilling results, a series of conclusions was made. The proposed technique was tested in the process of drilling 9500 m of horizontal shafts and its high information content and reliability was confirmed. This technology is not expensive and can be implemented on any field after equipping the station for geotechnical well testing with portable devices for determining the elemental composition of rocks. To replicate this technology to other fields, it is necessary to study the reference sections of target sediments from the point of view of layer-by-layer changes in the elemental composition of rocks.

References

1. Panchenko I.V., Nemova V.D., Smirnova M.E. et al., Stratification and detailed correlation of Bazhenov horizon in the central part of the Western Siberia according to lithological and paleontological core analysis and well logging (In Russ.), Geologiya nefti i gaza, 2016, no. 6, pp. 22–34. В В В В В В В 

2. Slavkin V.S., Alekseev A.D., Koloskov V.N., Some aspects of a geological structure and prospects of oil-bearing capacity of Bazhenovskaya suite in the West of latitudinal Priobye (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2007, no. 8, pp. 100–104.

3. Nemova V.D., Gavrilov S.S., Issledovaniya kerna otlozheniy bazhenovskogo gorizonta, kak osnova dlya interpretatsii dannykh seysmorazvedki (Research core of deposits of Bazhenov horizon, as the basis for the interpretation of seismic data), Collected papers “Petrofizika slozhnykh kollektorov: problemy i perspektivy 2014” (Petrophysics of complex reservoirs: problems and prospects for 2014), Moscow: Publ. of EAGE Geomodel', 2014, pp. 212–230, ISBN 978-94-6282-030-2.

4. Nemova V.D., Panchenko I.V., Localization of inflow intervals and storage volume of the Bazhenov formation, Sredne-Nazym oil field (In Russ.), Neftegazovaya geologiya. Teoriya i praktika, 2017, V. 12, no. 1, URL: http://www.ngtp.ru/ rub/4/11_2017.pdf

5. Nemova V.D., Panchenko I.V., The productivity factors of Bazhenov formation in Frolov megadepression (Western Siberia) (In Russ.), Neftegazovaya geologiya. Teoriya i praktika, 2017, V. 12, no. 4, URL: http://www.ngtp.ru/rub/ 4/46_2017.pdf


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