Russian Lateral (BKZ) Analysis

Abstract

This paper covers the essentials of the tools, and practice of basic Russian well logs and Russian log analysis techniques. Emphasis is placed on those tools used in Russia which are significantly different than their counterparts in other major petroleum producing provinces. The BKZ Kapotax is five Russian lateral electrical resistivity logs run at different spacings depending on the reservoir thickness. It is used to calculate true formation resistivity. The technique corrects for mud and borehole effects using response curves modeled for a lateral log. This technique uses different tool spacings, borehole size, mud resistivities, diameter of invasion and the resistivities of the five laterals. This paper presents the BKZ method for predicting the true formation resistivity from this combination of lateral logs. Laterals were the primary resistivity log recorded by Russians before the early 1980's. Now the induction conductivity log is also being used, but not in the BKZ technique for determining Rt. Only lateral devices are used for this determination. By using the BKZ method, quantitative information may be extracted from historically recorded data and allows improved evaluation of reservoirs in previously drilled wells. Introduction Oil and gas wells drilled in Russia are classified as either research wells or production wells. Research wells are drilled by the local geologic institutes known as Geologia and include exploration and delineation wells. Production wells are drilled by local production institutes called Neft, for the purpose of developing and producing delineated fields. Most research wells are evaluated with open hole logs such as spontaneous potential (SP), a combination of lateral and normal resistivities, conductivity, microlog, caliper, gamma ray, gamma-neutron, density and acoustic logs along with cores and well tests. In contrast to the relatively complete data package gathered from research wells, production wells generally are evaluated with an SP in combination with a combination of lateral logs recorded at different electrode spacings. This paper describes the methodologies used for log interpretation using the BKZ method in actual Russian production wells. Software under development or available today will greatly assist the evaluation of these resistivity logs. P. 171^

ReMo3D – an open-source Python package for 2D and 3D simulation of normal and lateral resistivity logs

“…However, boreholes, where significantly larger resistivity logging suites were run, can also be encountered. Laterologs and induction tools were known and utilized in those countries, but contrary to the Western countries normal and lateral tools were kept in favor and extensively used in the hydrocarbon prospecting industry until the 1990s when they started to be replaced by logging tools of Western design (Wiltgen & Truman 1993, Wiltgen 1994, Jakubowicz 1995, Tingey et al 1995, Vincent & Williams 1995.…”