The article deals with an actual problem of horizontal drilling- the presence of gaps from the LWD and WLL offset points. There is a high probability of overpassing the target interval while drilling horizontal wells, and as a result, a decrease in production rate. In these cases, the importance of gas logging increases. Gas logging is a set of studies designed to analyze the gas that is formed while drilling. The method is based on determination of volume and composition of gases in the drilling fluid coming to the surface from the well. It is a direct method; unlike other types of logging that solve the problem of identifying pay zones in the well section and their saturation. The results of gas logging while drilling provide information about reservoir saturation.
To date, there are several basic methods for analyzing the composition of a gas-air mixture that allow tracking the change in the reservoir saturation by the proportion of heavy and light hydrocarbons in the analyzed gas-air mixture. This makes it possible to determine the phase composition of hydrocarbons contained in the reservoir, as well as to identify interfluid contacts (gas-oil and water-oil).
This article is focused on the modern experience of using gas logging as an additional source of information for geosteering in complex geological and technological drilling conditions. Examples of operational determination of formation exposing and finding GOC according to gas logging data are considered.
Thus, it is shown that gas logging is a relevant method of well exploration, which allows reducing uncertainty in horizontal wells.
References
1. Martynov V.G., Geofizicheskie issledovaniya skvazhin (Well logging), Moscow: Infra-inzheneriya Publ., 2009, 960 p.
2. Luk'yanov E.E., Issledovaniya skvazhin v protsesse bureniya (Well surveys while drilling), Moscow: Nedra Publ., 1977, 248 p.
3. Pomerants L.I., Gazovyy karotazh (Gas logging), Moscow: Nedra Publ., 1982, 240 p.
4. Tarasova E.V., Quick evaluation of rock saturation by mud log (In Russ.), Karotazhnik, 2011, no. 10(208), pp. 10–22.
5. Luk'yanov E.E., Interpretatsiya dannykh GTI (Interpretation of mud logging data), Novosibirsk: Istoricheskoe nasledie Sibiri Publ., 2011, 944 p.
6. Haworth J.H., Sellens M., Whittaker A., Interpretation of hydrocarbon shows using light (C1–C5) hydrocarbon gases from mud-log data, The American Association of Petroleum Geologists Bulletin, 1985, V. 69, no. 8, pp. 1305–1310, DOI:10.1306/AD462BDC-16F7-11D7-8645000102C1865D
7. Pixler B.O., Formation evolution by analysis of hydrocarbon ratios, SPE-2254-PA, 1969, DOI:10.2118/2254-PA
8. Starosel'skiy V.I., Etan, propan, butan v prirodnykh gazakh neftegazonosnykh basseynov (Ethane, propane, butane in natural gases of oil and gas basins), Moscow: Nedra Publ., 1990, 186 p.
