An Example of Building a Petrophysical Model of Unconsolidated Gas-Saturated Laminated Sediments Using Advanced Wireline and Logging While Drilling Services

Abstract

Productive deposits of the Turonian age as part of the Kuznetsovskaya Formation are cover the eastern part of Western Siberia (Figure 1), but until recently they were not of wide industrial interest. Today, most of the gas reserves in Western Siberia are produced in the Cenomanian deposits, which are in the stage of declining production. The productivity of the deposits above Cenomanian layer has been established in many fields where the Cenomanian formations are productive. In general, in Western Siberia in the Turonian deposits, there are more than 3 trillion cubic meters of gas, which allows us to consider them as high-potential sources of gas reserves. The main difficulties in the industrial development of Turonian deposits are reduced permeability, high dissection, high content of clay fraction, high macro- and microheterogeneity of the reservoir, inconsistency of effective thicknesses in plan and section. In turn, the relatively low temperature of the reservoir predetermines the operation of the field in a mode close to hydration (Avramenko et all., 2019). Under these conditions, a good petrophysical baseline is essential to assess the exploration potential of the assets and design the development of the reservoir. Shaly gas-saturated formations are not a simple object for petrophysical modeling. Adding to this the low quality of the core material caused by the weak cementation of shallow deposits, we get a very nontrivial problem. On the other hand, modern horizontal well development scenarios dictate their requirements for petrophysical models. In other words, the petrophysical model must maintain its stability for any well logging regardless of the well trajectory (vertical or horizontal) and the logging method conveyance (wireline or while drilling). The authors of the paper carried out work on the development of a universal petrophysical model of the Turonian reservoir, for one of the fields in the region of the north of Western Siberia, based on a modern extended GIS complex.