Comprehensive Substantiation of a Horizontal Wellbore Inflow Model in a Fractured Carbonate Reservoir

Abstract

Abstract The practice of developing fractured reservoirs suggests that the description of the well-reservoir system often does not correspond to the behavior predicted by classical filtration theories for fractured systems (Warren-Root and others). This fact is very clear when analyzing the operation of horizontal wells, in which significant heterogeneity of the distribution of the inflow profile along the well. Thus, the reservoir cannot represents like a homogeneous system, and forecasting the operation of wells requires the use of new methods for describing reservoir systems. In the course of analyzing the operation of wells in one of the oil and gas condensate fields in Eastern Siberia, a deviation from the forecast parameters obtained by the traditional method is noted. In this regard, a detailed analysis of previously performed logs and well tests in order to refine the model of inflow to horizontal wellbores is detailed. At the initial stage, was performed a comprehensive analysis of the operation of the reference wells. These wells have the most extensive set of studies (PTA, PLT, advanced complex of well logging, micro imagers). The analysis revised the approach to the description of the inflow model. Further, the results scaled to the rest of the existing fund of producing horizontal wells. In the course of the analysis, our team revealed a significant deviation of the actual filtration model from earlier ideas about the operation of this reservoir. According to the results of combining various research methods in the reference wells, we revealed the predominant effect of local fractured intervals on the operation of the entire horizontal well. In this regard, the approach to the description of well productivity and the forecast of their operation revised. In addition, authors identified a significant influence of the degassing of reservoir fluid on well productivity, and the range of the target bottomhole pressure was determined. The acquired knowledge about the filtration model of reference wells was scaled for the entire exploration horizontal wells, which made it possible to identify patterns in the formation of productivity in the entire field. An approach has been developed to describe the operation of horizontal wells under the conditions of opening an unevenly fractured carbonate reservoir, based on a combination of PLT, well test and open-hole well logging. Additionally, authors studied various machine-learning algorithms to adapt the results of the interpretation of open-hole logging to PLT data. To predict the launch parameters and dynamics of horizontal well flow rates, the rejection of the filtration model in a homogeneous isotropic reservoir in favor of the inflow model to local fractured intervals is justified. This will make it possible to clarify the current levels of production in wells, optimize well operation modes, and make recommendations for conducting geological and technical measures.