Elaboration of criteria for laying wells of the operating stock of the Riphean carbonate reservoir in the central part of the Kamovsky arch of the Baikit anteclise based on 3D seismic data

Abstract

Summary The object of this work was a large oil and gas condensate carbonate field in Eastern Siberia. The target interval at the field is the riphean reservoirs, which are represented by an impermeable carbonate matrix permeated by a dense network of micro-macro cracks of various orientations, caverns and leaching intervals. The affected area was subjected to an active and multi-stage tectonic impact, which led to the widespread development of numerous low-amplitude, sub-vertical faults and fracture zones of a predominantly shear nature. The main intervals of the section are represented by the Archean basement, Proterozoic (Riphean-Vend), Paleozoic (Cambrian, Ordovician, etc.) and Upper (HCR) parts of the section. The Paleozoic part of the section consists mainly of Cambrian carbonate-halogen-sulfate rocks and traps, presumably of Triassic age. The wave pattern of the Cambrian rocks is characterized by relatively laterally sustained seismic reflections with a small number of interpreted faults. The shape of the wave pattern, or in other words, the seismic images/seismophations, are mainly high-amplitude, laterally sustained with increased reflection and impedance coefficients. Potential reservoirs in this part of the section are most often represented by relatively dense carbonates, which are characterized by a small number of secondary changes in carbonate rocks. The main risks when drilling GS are the presence of abnormally high absorption of drilling fluid (up to loss of circulation), the presence of tool failures, frequent wear of bits, the presence of silicification. More than half of the current fund of producing wells have a high gas factor or significant water cut. To solve the described problems, it was decided to create a number of criteria for laying horizontal wells, taking into account the seismogeological conditions of the section.