Three-dimensional geological modelling of the eastern and western parts of the Hovsan field according to geological and geophysical data

Abstract

The article considers the issue of volumetric modelling of productive formations of the Hovsan oil field using the PETREL software package. The productive horizons QaS-2 and QaS-3 of the Qala Suite of the Productive Series in the eastern and western parts of the Hovsan field were taken as the object of the study. Geological and geophysical data for the research area were used to construct the model. The Hovsan field is related to deposits of the Qala Suite in the western and eastern sections, separated by an industrially important oil-water zone. The deposits of the Qala Suite are divided into three horizons: (from top to bottom) QaS1 ― 57 m, QaS2 ― 70 m, and QaS3 ― 168 m. The total thickness of the Qala Suite is 250 m in the western part and 280 m in the eastern part. The article explains in detail the methodology for building 3D models of the eastern and western parts of the Hovsan field using both geological and well data for the research area. It also includes a petrophysical model of the eastern and western parts of the Hovsan field and a lithological cube for volumetric lithologymodelling. The paper shows that sands and sandstones (thickness 5―15 m), which are oil and gas reservoirs, are separated mainly in the upper and middle horizons, as well as in the top part of the lower layer of the lower horizon (thickness 30 m), which alternate with clay layers 2―3 m thick. The reservoir properties of the layers vary along the section and over the area. Although the Hovsan field has been in production for more than 70 years, 3D geological and geophysical modelling was carried out for the first time for the eastern and western parts of the Qala Suite, which is considered promising in terms of productivity.For the first time, the research area was studied in detail from the point of view of lithology, petrophysics, and oil and gas content in the inter-well space using modelling based on 3D seismic data.On the other hand, 3D models are the basis for solving issues such as hydrocarbon resource estimation,justifying the drilling of new wells, monitoring resource development, and assessing the impact of waterflooding and production well operations.Using three-dimensional models made it possible to realise both long-term and operational forecasting when monitoring the exploitation of hydrocarbon fields. Since the presence of new objects in the Qala Suite, considered promising in terms of productivity, is not in dispute, the study confirmstheir detection and monitoring with the application of three-dimensional models.