In densely deployed Wireless Sensor Network, a large number of sensor nodes in an event area observes the event information and sends information to the sink. Due to physical properties related to sensed event, the sensor observations are highly spatially correlated with respect to location of sensor nodes. In this paper we have proposed a heterogeneous correlation model that exploits the spatial correlation between each sensor nodes. Heterogeneous WSNs consists of normal nodes and advance nodes with different sensing range. With the help of sensor coverage model and location of sensor nodes, heterogeneous correlation functions are derived to analyze the correlation characteristics of observed information’s by sensor nodes. The case studies using heterogeneous correlation functions are performed to study the spatial relationship among sensor nodes. Finally, a correlated clustering algorithm is proposed for efficient medium access and clustering protocol for heterogeneous WSNs.