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 hy- draulic 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 res- ervoir 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 exclu- sive approach. The distribution pattern was revealed by interwell HU correlation using modified depositional cycles as a framework, an integration step that qualitatively examines prediction accu- racy. 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.