Statistical verification of hydraulic units in a heterogeneous reservoir of the Liaohe Oilfield

Abstract

The Liaohe Oil Field has passed peak production and correct discrimination of hydraulic units (HU) has vital significance for forecasting remaining oil distribution in a petroleum reservoir, enhancing the recovery ratio and adjusting development plans. A unified multi-parameter cluster analysis and fuzzy quality synthetic evaluations have been used for the identification of reservoir hydraulic units. This paper analyzes three predictions within Block Shen-95: intersection of multiple well-logs, independent mulitple well-logs and mutually exclusive multiple well-logs. HU has been delineated to conveniently compute permeability and serve as the basis of a structural model for enhanced simulation study. HU has been defined by the flow zone indicator concept using a modified Kozeny-Carmen equation. The Bayesian method was used to predict HU at uncored wells by constructing a probability database and then integrating established HU and well-log responses at cored wells. HU has then been inferred from the database using well-log responses. Estimated permeability from predicted HU gave an overall improved permeability match when compared with traditional statistical methods. The method proved most favourable when using mutually exclusive multiple well-logs, most significant by integrating reservoir performance with HU distribution and indicating that reasonable prediction had been obtained at uncored wells using this mutually exclusive approach. The distribution pattern was revealed by interwell HU correlation using modified depositional cycles as a framework, an integration step that qualitatively examines prediction accuracy. Detailed analysis has been carried out to determine and verify the characteristics of each kind of flow unit, providing a detailed geological basis for control of the oil field.