[en] The performance of the method of angular moments on the ΔΓ_s determination from analysis of untagged decays B_s⁰(t), B_s⁰ bar (t) → J/ψ(→ l⁺l^-)φ(→ K⁺K^-) is examined. The results of Monte Carlo studies with evaluation of measurement errors are presented. The method of angular moments gives stable results for the estimate of ΔΓ_s and is found to be an efficient and flexible tool for the quantitative investigation of the B_s⁰→J/ψφ decay. The statistical error of the ratio ΔΓ_s/Γ_s for values of this ratio in the interval [0.03, 0.3] was found to be independent of this value, being 0.015 for 10⁵ events