As the exploration and development in the oil and gas industry intensify, the total costs incurred by oil and gas companies escalate annually. Depletion of oil and gas assets constitutes approximately half of these total costs. Consequently, managing reserves depletion emerges as a critical strategy for cost reduction. Proved Developed(PD) reserves serve as a pivotal factor for calculating the depletion of oil and gas assets and, in turn, influence the overall costs borne by an company through depletion charges. This paper investigates the factors influencing the depletion of oil and gas assets, explores the quantitative relationship between depletion, operational expenses, net oil and gas assets, production levels, and PD reserves. A case study is carried out to perform a sensitivity analysis on the operational costs associated with depletion reserves across various producing blocks, culminating in the formulation of a quantitative depletion allocation model for depletion. Recommendations for controlling depletion are proposed, aiming to foster a scientific and efficient linkage between depletion provision and SEC reserve evaluation. These strategic suggestions are intended to empower oil and gas companies to proactively engage in reserve assessments, manage the depletion of oil and gas assets effectively, diminish total costs, and optimise the asset structure within the oil and gas industry.