Experience of study of capillary characteristics of fractured-cavernose carbonate deposits. Challenges and solutions

Abstract

Introduction. Due to the strong difference between carbonate reservoirs and terrigenous reservoirs in the structure of the pore space and other properties, these deposits require special approaches to study. For this reason, the authors have been conducting methodological work in this area in recent years. This work is a summary and summarizes the accumulated experience of the authors in the field of capillary core investigations of carbonate reservoirs.

Aim. To develop practical recommendations for laboratories. To determine the directions for further improvement of methods for studying capillary properties and carbonate deposits.

Materials and methods. The semipermeable membrane method (study of capillary properties) was used as the main method. The following methods were used as auxiliary methods: centrifugation (capillary properties), gasvolumetric (open porosity), liquid saturation (pore volume) and layered NMR (water distribution in the sample). The capillary palette method was used to generalize the capillary curves. The studies were carried out mainly on limestones of Eastern Siberia (Nepsko-Botuobinskaya anteclise, Lower Cambrian, Osinsky horizon) and other regions with fractured-cavernous and intercrystalline types of porosity. Samples with a diameter of 38 mm and a length of 50–60 mm were used.

Results and conclusions. As a result of the work carried out, the experience of capillary studies of carbonate rocks was generalized. The main problems and factors affecting the quality of measurement results are described. The directions of further development of the methods were outlined. Practical recommendations on performing experiments and processing the results are given.