As an important reservoir type in the Bohai Bay Basin, China, lacustrine beach and bar sands which refer to the shallow water complex deposited mainly by nearshore, delta-rim and buried hill-related beaches as well as longshore bars were developed in a particular stage in the evolution of those faulted Cenozoic continental depressions. In the Chezhen Depression, for example, the Second Member of the Oligocene Shehejie Formation (abbr. as Es2 hereafter) formed during the rifting-to-thermal subsidence transitional stage. Although well developed in Es2, beach and bar sands are difficult to recognize owing to their relative thinness. The paper summarizes sedimentary characteristics of lacustrine beach and bar sands on cores and logs. Low-angle cross-stratification, swash stratification, as well as occasional small-scale hummocky cross-stratification resulted from storms can be observed in beach and bar sands. The paper distinguishes bars and beaches from each other in Es2 mainly based on the grain-size, bed thickness, facies succession and log responses.In order to predict the distribution of beach and bars, a chrono-stratigraphic correlation framework of Es2 in the study strata is established using a high-resolution sequence stratigraphic approach. Es2 strata are sub-divided into six medium-scale cycles and the mapping of the highfrequency cycles allows the geographic and stratigraphic distribution of both beach and bar sands to be predicted. The study shows that beach and bars are better developed in times of base-level fall than in base-level rise. Factors such as lake-level fluctuation, sediment supply, palaeogeomorphology and palaeowind direction have exerted control on the formation and distribution of beach and bar sands. Finally, the genetic pattern of beach and bar sands in the Es2 unit has been constructed, which provides a foundation for the prediction of beach and bars reservoir in continental basins in general.

Through the studying of heavy mineral assemblages and ZTR index variation features, this paper analyses the provenances and sedimentary systems of Saertu reservoir in Cretaceous of Jiangqiao-Pingyang area, western slope zone in northern of Songliao basin. It is concluded that there are three major sedimentary systems in the Saertu reservoir depositional period, named the Nehe-Yian sedimentary system in Northeast, Yingtai sedimentary system in Southwest, Qiqihaer sedimentary system in Northwest. The intensity and influence scope of the sedimentary systems in sedimentary period of SaII+III, SaIand Sa 0 reservoir changed. During the sedimentary period of SaII+III reservoir, research area is mainly controlled by the Qiqihaer and Yingtai sedimentary systems, the control action of Nehe-Yian sedimentary system in the research area is faint. During the sedimentary period of SaIreservoir, Nehe-Yian sedimentary system control the sedimentation of mainly region in research area, the control range of Qiqihaer sedimentary system has shrunk to the West of Jiangqiao area, the Yingtai sedimentary system dropped out of the research area. During the sedimentary period of Sa 0 reservoir, the control action of each sedimentary system basically inherited the distribution pattern of the sedimentary period of SaIreservoir, but the source supply capacity weakened further.

Dielectric measurements, in the frequency range from 100 Hz to 15 MHz, were carried out using an insulating film method, on shaly and clean sandstone samples, dry, oil-impregnated, partially or fully saturated with fresh water or solutions of NaCl, at different concentrations. The results show that two kinds of polarization relating to interface dominate: the inner surface polarization (ISP) at the pore surface in rocks and the outer surface polarization (OSP) on the outer surface of the rock sample. Both ISP and OSP are of the Debye type and can be fitted very well using the Cole-Cole equation. The dielectric spectra of ISP reflect the length scale of pore size or throat size, whereas the relaxation strength depends heavily on the inner pore surface area. Clay contributes to dispersion in rocks, mainly through increasing the inner surface. When the effect of water content is minimized, the dielectric properties measured on brine-wetted rock samples show great salinity dependence. The increase in salinity shifts the relaxation spectra to the high frequency end; it also enhances the relaxation strength. In the frequency range studied, no dispersion in dry and oil-saturated samples has been observed, which underscores the key role played by water in dielectric polarization in rocks.