Search for overlooked deposits in the well-studed deposits of coastal-continental genesis

Background. We present the results of identifying promising objects (overlooked deposits) in well-studied fields under the conditions of lithologically heterogeneous reservoirs without disclosing the methodological principles of the developed approach in order to illustrate the possibilities of further work in mature fields.

Aim. To illustrate a promising direction in studying coastal-continental deposits with an extensive history of geological and geophysical studies with a focus on searching for local changes in lithology.

Materials and methods. Forecasting was carried out based on attribute values for the studied intervals with high correlation coefficients, as well as the values of gas-saturated and water-saturated thicknesses in wells. The available information was used to develop an algorithm of actions for identifying promising objects in areas with possible overlooked deposits. This algorithm allows the approach to identifying promising objects to be formalized and automated. A mathematical approach was used to determine the boundary value of the seismic attribute that records gas-saturated areas, which are independent of the structural factor.

Results. The results obtained by applying the tested method justify the complex lithological structure of the section under study and confirm the possibility of extending mature fields. The described approach represents a solution to the problem of searching for overlooked deposits in open fields of coastal-continental genesis associated with the lithological factor of trap formation.

Conclusion. The results can be used in the construction of 3D geological models to clarify the structure of sections. The application of the developed approach made it possible to identify overlooked lithological objects. The constructed maps of aggregated gas-saturated thicknesses will facilitate optimal location of transit wells to underlying deposits for the purpose of concurrent study of the section. The results obtained confirm the possibility of the existence of non-structural deposits in such sections.

1. Levyant V.B., Ampilov Yu.P., Glogovsky V.M., Kolesov V.V., Korostyshevsky M.B., Ptetsov S.N. Guidelines for the use of seismic exploration data (2D, 3D) to calculate oil and gas reserves. Moscow: TsGE, MPR, 2006. 39 p. (In Russ.).

2. Pozametier G., Allen J.P. Sequence stratigraphy of terrigenous deposits. Basic principles and application. Moscow — Izhevsk: Institute of computer research, 2014. 436 p. (In Russ.).

3. Potapova E.A., Shakirov R.R., Evdoshchuk A.A., Levanyuk T.V., Leontyeva O.S. Creation of a sequence stratigraphic model to clarify the geological structure of coastal-continental deposits of the Tanopcha suite. Georesources. 2024. Vol. 26. No. 3. P. 43—50 (In Russ.).

4. Samoilova A.V., Afanasyeva M.A. Approaches to the study of non-anticlinal traps in Western Siberia and the prospects for their mapping. Exposure Oil Gas. 2020. No. 6. P. 25—30 (In Russ.).

5. Dolson J., Marfurt K., He Z., Horn B.W. Advances and perspectives on stratigraphic trap exploration-making the subtle trap obvious. Papers of AAPG 2017 Middle East Region Geosciences Technology Workshop, Stratigraphic Traps of the Middle East. Muscat, Oman. 2017. 11—13 December.

6. Pearson K. Geologic models and evaluation of undiscovered conventional and continuous oil and gas resources — Upper Cretaceous Austin Chalk, U.S. Gulf Coast U.S. Geological Survey. Reston, Virginia, 2012.

7. Stirling E.J., Fugelli E.M.G., Thompson M. The edges of the wedges: a systematic approach to trap definition and risking for stratigraphic, combination and sub-unconformity traps. Geological Society, London: Petroleum Geology Conference Series, 3 February 2017. No. 8. P. 273—286.

8. Windows N.S. Non-anticlinal traps and their examples in oil and gas provinces. Petroleum geology. Theory and Practice. 2012. Vol. 7. No. 1. P. 1—14