## 2 Materials and Methods
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Job No.** & **Deposit** & **Formation** & \begin{tabular}{c} **Skin Factor** \\ **Actual Change** \\ \end{tabular} & \
\begin{tabular}{c} **Skin Factor** \\ **Predicted Change** \\ \end{tabular} &
\begin{tabular}{c} **Deviation,** \\ **\%** \\ \end{tabular} \\ \hline
1 & Ozyornoye & Bashkirian-Serpukhovian & \(-\)3.40 & \(-\)3.27 & 3.82 \\ \hline
2 & [PERSON] & Bashkirian-Serpukhovian & \(-\)2.80 & \(-\)2.90 & 3.57 \\ \hline
3 & [PERSON] & Tournaisian & \(-\)3.20 & \(-\)2.94 & 8.13 \\ \hline
4 & [PERSON] & Famennian & \(-\)2.50 & \(-\)2.74 & 9.60 \\ \hline
5 & [PERSON] & Bashkirian & \(-\)2.70 & \(-\)2.53 & 6.30 \\ \hline
6 & [PERSON] & Tournaisian-Famennian & \(-\)2.60 & \(-\)2.84 & 9.23 \\ \hline
7 & [PERSON] & Tournaisian & \(-\)2.40 & \(-\)2.57 & 7.08 \\ \hline
8 & Shagirtsko-Gozhanskoye & Vereiskian (V\({}_{3}\)V\({}_{4}\)) & \(-\)2.90 & \(-\)2.71 & 6.55 \\ \hline
9 & Dorokhovskoye & Tournaisian & \(-\)2.80 & \(-\)2.83 & 1.07 \\ \hline
10 & Pavlovskoye & Tournaisian & \(-\)3.00 & \(-\)2.96 & 1.33 \\ \hline
11 & Sibirskoye & Bashkirian-Serpukhovian & \(-\)2.90 & \(-\)2.70 & 6.90 \\ \hline
12 & Churakovskoye & Tournaisian & \(-\)2.80 & \(-\)2.58 & 7.86 \\ \hline
13 & Rassvetnoye & Bashkirian & \(-\)3.10 & \(-\)3.26 & 5.16 \\ \hline
14 & Rassvetnoye & Bashkirian & \(-\)2.50 & \(-\)2.79 & 11.60 \\ \hline
15 & [PERSON] & Tournaisian & \(-\)2.60 & \(-\)2.77 & 6.54 \\ \hline
16 & [PERSON] & Bashkirian-Serpukhovian & \(-\)2.80 & \(-\)2.68 & 4.29 \\ \hline
17 & [PERSON] & Bashkirian-Serpukhovian & \(-\)2.90 & \(-\)2.64 & 8.97 \\ \hline
18 & [PERSON] & Tournaisian & \(-\)2.70 & \(-\)2.85 & 5.56 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparison of skin factor actual change with predicted values. Figure 4: Comparison of actual and calculated increase of cumulative oil production. As it can be seen, the relative errors presented in Table 1 vary in the range from 1.07% to 11.60%, which is an allowable deviation. For more accurate analysis and determination of the significance of the relationship between the two sets of values, i.e., actual and calculated changes in the skin factor, the main statistical indicators shall be used. As determined by calculations using STATISTICA software, the Student's \(t\) test and the achieved significance level constitute 0.079 and 0.937, respectively, while standard deviations do not exceed allowable value range, as well, i.e., the internal scatter about the mean is insignificant. The conducted analysis indicates the high significance of the relation between actual and design data, which testifies to the effective approach to the prediction of HAT results using the proposed technique. Comparative analysis of actual and design results has afforded the authors of this work, the assurance in the idea of using [PERSON]'s formula in the basis of predicting the success of acid treatment. An example of the practical application of the proposed technique on the existing well, which consists in determining the HAT effectiveness using hydrodynamic simulation, is given below in this paper. In July 2019, an oil-producing well of the Kokuyskoye oil field in Perm Krai, entering the Tournaisian strata, was determined as the target facility for the hydrochloric acid treatment job. To evaluate the perfection of the proposed method of predicting the acidizing effectiveness, the authors have presented a comparison of actual and design production rates for the subsequent 6 months of operation of the well under study. Additionally, using Tempest MORE hydrodynamic simulator, a geotechnical procedure was designed, and the technological effect of planned acid treatment of bottom-hole zone for the following 10 years was analysed. FLUXOCORE-210 (grade P) acid composition was selected as an agent, as it has proved to be excellent in the field experience of oil recovery stimulation methods and has shown good results in laboratory studies presented in the paper ([PERSON], 2019 [19]).