In order to explore the water displacement efficiency and its influencing factors of high porosity and high permeability unconsolidated sandstone heavy oil reservoir through the thermal production boundary in the mode of large volume liquid extraction and cold production,taking LD oilfield in Liaodong mining area of Bohai Sea as an example, the systematically study on oil displacement efficiency of 2 000 PV high multiple water was carried out with flow rates were 1.0,7.5,15.0 mL/min.At the same time,combined with mercury injection,X?ray diffraction,whole rock and gas permeability measurement,the liquid extraction system can be optimized,and the influence of various factors on the water oil displacement efficiency of this type of heavy oil reservoir after liquid extraction was analyzed as well.The experimental results show that the differences of reservoir geological characteristics such as micro pore?throat structure,interstitial content and permeability have a great influence on the displacement characteristics after liquid extraction. The worse micro pore?throat structure would induce a higher the interstitial content, inferior permeability and lower high PV water flooding efficiency.Compared with the direct liquid extraction method, the step?by?step liquid extraction method can achieve higher water flooding efficiency.For this type of heavy oil reservoir,it has the best liquid extraction range.If the amplitude is too large, it is easy to cause the front edge to burst, and reduce the micro sweep. It should be controlled at 7.5 times. The experimental results can effectively guide the exploitation of residual oil by using horizontal well extraction in heavy oil reservoirs.

Bohai L oilfield has undergone multiple adjustments since it was exploited, such as well pattern internal infilling, changing well patterns, and reversing lines. The scattered distribution of remaining oil on the flat and extremely complicated vertical flooding law resulted in difficulty for tapping the remaining oil. Based on the data of core, well logging, seismic, production dynamic and other results, the thick reservoir can be comprehensively characterized, so as to guide the remaining oil fine characterization and potential development. The results show that the plane contact styles of single sand body is mainly in butt type, and the vertical overlap mainly in cut type. The remaining oil of the southern vertical accretion type leaf body is mainly concentrated near the vicinity of the fault, the buried hill area and the sand?body deposition margin, which can be tapped using directional wells. The remaining oil of the central prophase frond is mainly concentrated in the top of the thick sand body and the lower part of the thin interbe, which can be tapped using horizontal wells.