| Minfeng area is located in northeast Dongying depression. Chenjiazhuang uplift is adjacent to its north, and Qingtuozi uplift is adjacent to its east. Thick source rocks developed during Es3 and Es4 depositional period, and abundant reservoir sand developed surrounding Minfeng sag, which provided advantageous reservoir-forming conditions, and has become the next importantly reserve replacement area of exploration. Using core drilling, logging, and seismic data, and sequence stratigraphy, sedimentology, petroleum geology theories and technologies, the sedimentary characteristics, reservoir characteristics, and reservoir-forming conditions in Es3 and Es4 Formation of Minfeng Sag is systematically studied.The formations are fully developed in Minfeng area, and the formations Es4x, Es4s and Es3z are delicately divided, additionally, the formation Es4-x and Es3z-x are respectively divided into 6 sand sets and the formation Es4x is divided into 4 sand sets.The comprehensive analysis of heavy minerals, glutenite content and features element distribution indicated that northern, eastern and southeastern source systems developed during Es3 and Es4 depositional period. Under the control of the three source systems, nearshore subaqueous fans, fan deltas, river-deltas, deep-water slope turbidite fans, landsliding turbidites and slope turbidite fans developed in the study area. During the Es4 depositional period, nearshore subaqueous fans from the north source system developed; during Es3z-x depositional period, river deltas and fluxoturbidites from eastern and southeastern source system developed; lower Es3 depositional period was the stage that source system changeed from north to east.Because of the steady distribution of several salt-gypseous horizons above Es4x layer, two hydrocarbon systems that are upper salt bled and lower salt bled are formed. The source rock of the lower salt bled hydrocarbon is a suite of well high maturity source rock, which was new found in 2007. The gas and petroleum of reservoirs in Es4x layer are injected in three times, and reservoirs are nearshore subaqueous fans and condensate reservoir, they can be recognized as both reservoirs and source rocks. The available reservoirs are middle fan subfacies, which have traits of lower porosity, lower permeability, and the forming of which is controlled by physical characters. The reservoirs are enrich in middle fan subfacies, overlapped, continuous and sealed by root fan subfacies.There are three suites of source rocks for the upper salt bled (Es4 and Es3z-x), the Es3z one is not the main source rock, and the Es4s and Es3x are main source rocks. The reservoirs accumulation type are divided into other resource type and self resource type.The lithology of Es3 and Es4s reservoir in Minfeng sag was approximately A1 stage of meso rock. Reservoir pore space was mainly secondary solution pore. Reservoirs in Es4s formation are predominately glutenite fans lithologic reservoirs, while reservoirs in Es3z formation are predominately turbidite lithologic reservoirs. The distribution and abundance of hydrocarbon are mainly controlled by macroscopic structural background, sedimentary facies, reservoir thickness, sealing, pressure and complex fault structure styles. The outlook that sideway sealing by root fan subface is proposed, the method how to explore nearshore subaqueous fans reservoir changed from structural reservoir to lithologic reservoir.Overall, 21favorable exploration targets are proposed, and 12 of them are deployed for exploration, additionally, the reported dominate geological reserves are 48,840,000 ton, while the predicted geological reserves are 10,110,000 ton. |
PDF Full Text Request