A Probabilistic Comprehensive Evaluation Method for the Fracability of Unconventional Hydrocarbons Reservoir Considering Description Uncertainty of Target Formation

Fracability evaluation is a crucial basis for fracturing and production enhancement in tight reservoirs. Due to the complexity of the geological environment, factors influencing reservoir fracability exhibit significant uncertainty. Ignoring the uncertainty of relevant parameters and conducting fracability evaluation based on deterministic parameters may lead to deviations from actual fracability results. To address this issue, this paper proposes a comprehensive evaluation method for the fracability of unconventional oil and gas reservoirs, considering reservoir description uncertainty. Based on fundamental evaluation methods, a reservoir fracability evaluation model is constructed, incorporating the Monte Carlo stochastic simulation method to determine the total probability distribution of the reservoir fracability evaluation index. This approach enables a more scientific and reliable evaluation of reservoir fracability. The research results indicate that the assumed distribution of input parameters has a certain impact on fracability evaluation results, with normal distribution demonstrating significant disturbance resistance. Additionally, brittleness index is found to be the most sensitive factor affecting fracability evaluation. The proposed evaluation method and insights can provide theoretical references for the fracability assessment of highly heterogeneous tight reservoirs.