The magmatism can affect reservoir characteristics, and it can guide the oil and gas exploration. Through the microscopic identification and geochemical analysis, we studied the intrusive rocks in the Bachu-Yijianfang area. The composition of gabbro and diabase in the Bachu-Yijianfang area shows that w(SiO2) 39.91%-44.62%,w(K2O+Na2O) 3.04%-3.95%, and w(Na2O)/w(K2O) 2.32-2.8;the rock is rich in Ba with a negative Sr anomaly;ΣREE (106.72-158.15)×10-6, LREE/HREE 5.44-5.89, LaN/YbN 5.124-5.442, and δEu 1.091-1.237. The chemical characteristics and tectonic diagram show that the rock occurs in a typical within-plate environment,and belongs to the Na-rich alkaline series. Field observation and laboratory analysis results show that the formation of clay minerals makes the reservoir properties of carbonate adjacent to the intrusive rocks not good; then, for the carbonate reservoir with acertain distance from the intrusion, it is better in property due to the enhanced fluids dissolution.