Characteristics and Genesis of the Es_(1) Productive Sandstone Reservoir(Paleogene),Nanpu Sag,East China

The Shahejie Formation is a fundamental rock unit for hydrocarbon exploration and production in the Nanpu Sag,Bohai Bay Basin.Methodology including thin sectioning,core observations,fluorescence,scanning electron microscopy,cathodoluminescence,fluid inclusion,laser scanning confocal microscopy and geochemical analysis(C,O isotopes)were all utilized to investigate the reservoir characteristics and origin of the Es_(1)Sandstone.Thin section study showed that the reservoir rock consisted of feldspathic litharenite and lithic arkose.The reservoir pores are categorized as intergranular pores,fracture pores,dissolution pores and intergranular cement dissolution pores.The studied sandstone had good porosity(0.05%–35%)and permeability(0.006–7000 mD).The Es_(1) reservoir is classified as a fractured reservoir,a primary intergranular pore-associated reservoir and a dissolution reservoir.Deposition,diagenesis and tectogenesis are the main factors that played important roles in the development of the reservoir.Sedimentation is the foundation and assumption for reservoir development,but the effective reservoir is primarily controlled by primary pores,fractures,lithofacies,tectonic elements and dissolution pores.Moreover,compaction,fracture filling and cementation were the primary sources of reservoir densification.The reservoir was progressively formed through the influence of different geological and diagenetic events.The present study provides significant information and references for hydrocarbon exploration and development in the Nanpu Sag.

A 75 GHz regenerative dynamic frequency divider with active transformer using InGaAs/InP HBT technology

This letter presents a high speed 2 ： 1 regenerative dynamic frequency divider with an active transformer fabricated in 0.7μm InP DHBT technology with fTof 165 GHz and fmax of 230 GHz. The circuit includes a two-stage active transtbrmer, input buffer, divider core and output buffer. The core part of the frequency divider is composed of a double-balanced active mixer （widely known as the Gilbert cell） and a regenerative feedback loop. The active transformer with two stages can contribute to positive gain and greatly improve phase difference. Instead of the passive transformer, the active one occupies a much smaller chip area. The area of the chip is only 469 × 414μm2 and it entirely consumes a total DC power of only 94.6 mW from a single -4.8 V DC supply. The measured results present that the divider achieves an operating frequency bandwidth from 75 to 80 GHz, and performs a -23 dBm maximunl output power at 37.5 GHz with a 0 dBm input signal of 75 GHz.