Application of Q-model principal factor analysis and clustering method in evaluation on sandstone reservoirs of the Neogene in Huatugou Oilfield, Qaidam Basin

Based on the data of 244 wells, the sandstone reservoirs of the Neogene in Huatugou oilfield, Qaidam Basin is tentatively evaluated with Q-model Principal Factor Analysis (PFA) and Fast Clustering Method (FCM). In order to quantitatively analyze the characteristics of the reservoirs and the relation between the characteristics and the sedimentary facies of the reservoirs with the evaluation results, the method is put forward as follows: firstly, the scores of the principal factors obtained by PFA are normalized; then, the normalized scores are multiplied with the weights of the corresponding principal factors and added to get the scores of the samples. The reservoirs are evaluated by applied FCM with the scores of the samples. After analyzing the characteristic of the sandstone reservoir in the area with the statistic of the evaluation results, the authors conclude that, for the characteristic of the reservoir, the lower Youshashan Formation of the Neogene in Huatugou oilfield is better than the upper Ganchaigou Formation, the braided channel deltaic front is the best sub-type facies, the river-mouth bar sand body is the best microfacies sand body, and the submarine distributary sand body and turbidite sand body follow. Authors' method is quantitative and contains the explicit geological significance, so it is worthy of being generalized.