Abstract: To address the problem that it is difficult to quantitatively characterize the influence range of volcanic rocks on the physical properties of sandstone reservoirs, the three typical contact relationships between volcanic rocks and sandstone reservoirs were summarized using dynamic and static data from the Bohai X Oilfield. A multi-layered commingled production composite reservoir model was established using the theoretical method of well testing, the "homogeneous + composite reservoir" model was used as an example to analyze the influence of the boundary radius of homogeneous layer, the mobility ratio of inner and outer zone of composite layer, the storage capacity ratio of inner and outer zone of composite layer, and the radius of inner zone of composite layer on the pressure dynamic curve, and the model was applied to the well testing interpretation of Well A1 in Bohai X Oilfield. The study results show that the pressure dynamic curve can be divided into five stages according to the pressure derivative curve morphology, which are wellbore storage stage, early transition flow stage, transition flow stage from the inner zone to the outer zone of the composite layer, mixed flow stage between the outer zone of the composite layer and the homogeneous layer, and multi-layer boundary response stage. The high fitting accuracy of Well A1 test well further verified the reliability of the model. The physical properties of the sandstone reservoir deteriorated within about 300.0 m from the volcanic rocks. Combined with the range of volcanic rocks portrayed by the static data, the network deployment of the 2 adjustment wells in the Bohai X Oilfield was guided, and the specific productivity index after production was 4.0 to 6.0 times of that of Well A1, with remarkable effect. The research results have some implications for well testing interpretation, well network deployment and efficient development of sandstone oilfields in volcanic rock development area.

Key words: volcanic rocks, multi-layer commingled production, composite reservoir, contact relationship, well testing interpretation, Bohai Oilfield