Formation And Analysis Of Typical Neopaleozoic Hydrocarbon Reservior In Linqing Super-depression

Linqing Depression has experienced more than 40 years'oil/gas exploration history, middle-shallow formation is provided with rather high exploration and development degree. Reservoirs of shallow depth, high abundance, large size have been found, exploration difficulties are increasing, thus, Deep exploration becomes a certain trend of future exploration especially the neopaleozoic exploration. Years of explorations indicate that, the Linqing depression neopaleozoic oil gas show is very active and has wide distribution range.The discovery of Wengu2 well and Gaogu4 well coal-formed gas reservoirs showed that Linqing neopaleozoic possess the geology conditions of coal-formed oil gas reservoir, Neopaleozoic petroleum system has a favorable exploration prospect. The main study objects of this paper are the reservoirs of which source roclk are coal-permian coal series formation. Based on comprehensive geology analysis, the distribution of neopaleozoic reservoir (oil gas show) is identified. By testing, oil and gas are only found in 7 wells and oil gas show are mainly distributed in east Linqing depression and Dongpu sag. Low production hydrocarbon flows are found in Kai33, Kai35, Wengu1, Magu5 and Bai56 wells of Dongpu sag, while industrial hydrocarbon flows are found in Wengu2 well of Dongpu sag and Gaogu4 well in the south of shenxian county.This paper takes full advantage of existing drilling, logging, seismic and analyzing testing data and previous research findings, optimized two typical neopaleozoic reservoirs with industrial hydrocarbon flows, Wengu4 and Gaogu4 well reservoirs. Detailed dissectings are performed on reservoir forming geology background, basic conditions of reservoir forming, reservoir forming evolution andso on, and failure analysis is conducted on the falilures of Gaogu4 well exploration.By the comparative anatomy of typical reservoirs, reservoir forming modes and main controlling factors are summarized. A conclusion is made that neopaleozoic reservoirs have the characteristics of proximal forming, secondary hydrocarbon generation, tectonic concentration and high fault lateral sealing ability. The preferred exploration area should be the traps where neopaleozoic formation are well developed, higher evolution degree was not reached in neopaleozoic rock source before paleogene, while since later paleogene the depth of source rock reached higher than secondary hydrocarbon generation peak, the faults activity was weak in secondary hydrocarbon generation period, and the traps have the property of forming effective lateral obstruction conditions. Based on the analysis and summary of the accumulation characteristics in the different areas of Linqing depression, we have a forecast on the advantageous exploration areas in the upper Paleozoic of Linqing depression. The most favorable zones contain the East North Qingzuji, Huzhuangji, Hubuzhai, Wenliu, Fangu 1 well(north), Dezhou trough, Shenxian trough, the uplift in the trough, the second high-leve and the other high structural parts in the interior of Guanxian trough. The potentially favorable zones are Weixian area in the southwest of Qiuxian trough, south Handan trough, and Menggangji in the southwest of Dongpu trough.