Research Of Es₂ High Resolution Sequence Strata And Beach-dam Sandstone In The Dawangbei Area

The Dawangbei Subsag is a structure sub-unit of the middle of Chezhen Sag.belong to Jiyang Depression. The second member of Shahejie Formation (Es2) is important one of oil-bearing series of strata of the Dawangbei Subsag. The Dawangbei Subsag has more subtle reservoir exploration potential. However, Es2 in the transitional period from fault to sag, the beach and dam sand is the main reservoir type, its wide distribution area, buried shallow wells with a long paragraph, types of complex hydrocarbon accumulation in the structure, sediment accumulation and has its uniqueness, unlike other layer of, no systematic study.The main purpose of this subject through Es2 of the sequence of high-precision, high-resolution establishing sequence stratigraphic framework, through Es2 facies types and distribution of sedimentary system and achieve forecast sand Spatio-temporal distribution; through research, exploration Sec against sand reservoir thin (generally 1 to 5 m), lateral continuity of poor, non-homogeneous macroscopic characteristics of the intensity of the beach sand dam reservoir prediction.The research to drilling, logging, seismic testing and analysis of information-based, application sedimentology, high resolution sequence stratigraphy, reservoir geology, and other theories, in the master structure, stratigraphy, and other basic geological characteristics on the basis of oil, use of seismic, logging phase sedimentary facies, seismic attribute analysis techniques, through the analysis phase Well, sedimentary environment analysis, the direction of the source of reservoir properties such as a large number of studies, the establishment of the Dawangbei Subsag deposition system Sec sand and sand depositional model, the sand clear of the space-time distribution, and formation of an effective set of applicable to the beach sand dam reservoir prediction.The innovation in this project is mainly due to: (1) seismic sequence interface on the basis of identification, according to Cross sequence stratigraphy of the principle of "deposition datum changes would be reflected in the deposition often stacking patterns," and stacking patterns with Backstepping references to the relative rate of change in size, at all levels, so as to identify the sequence of interface and the flood plain. GR curve to strike a sand curve, and because of this space can accommodate changes in the formation of the multi-formation cycle curve. (2) summed up the beach and dam sand of the sedimentary characteristics, the first time the "Dam" sand and the "Beach" sand identifiers. Beach and dam sand vertical fine ~ rough ~ fine symmetrical rhythm, sandstone and shale for the gradual contact between sedimentary structure to reflect weaker shallow lake foreshore hydrodynamic conditions, as well as the role of two-way flow of the shallow water features, including: Small cross-stratification, wavy bedding, composite bedding, lenticular bedding, gravel and mud storm waves slump tectonic deformation, and other main level and see traces of symmetric wave interference wave marks, mudstone in the development of biological burrows, carbon crumbs , bioturbation. "Dam" sand, sandstone mainly fine powder, sand thickness larger, sustained small vertical fine ~ rough ~ fine symmetry rhythm or small upward thicker anti-rhythm; mudstone and sandstone between the gradual contact with more grey Green and gray mudstone shale formation lithology combination of sedimentary structure type wavy bedding, small cross-stratification, washing bedding, composite bedding and storm wave formation of the mud and gravel slump mainly tectonic deformation. "Beach" sand, mudstone siltstone mainly silty shale, sandstone thickness less frequent among sand layer, a thin, vertical fine ~ rough ~ fine symmetric cycle; mudstone and sandstone contacts between the graded multi Purple brown and green and grey mudstone shale formation lithology combination of common sedimentary structures are: small cross-stratification, wavy bedding, composite bedding, lenticular bedding, level and see traces of symmetric wave interference wave marks, mudstone in the biological burrows, carbon dust, bioturbation, and other more developed. (3) Recognition of the dam sand beaches and the thickness of the oil on the characteristics of seismic attributes reflect. And the amplitude values are related to the thickness of sandstone, in the calibration of record on the basis of the average trough amplitude can be used effectively predict reservoir distribution, waveform classification method can be used to better predict effective reservoir thickness and distribution of oil.Through this research projects in the, first, that the The Dawangbei Subsag beach and dam sand of the favorable exploration target area, and was recommended to adopt exploration wells 6, the Da 373 Block reported proved area of 7.4 km2, Proven oil reserves in 380×104t; second is the establishment of apply to the Dawangbei Subsag beach and dam sand exploration ideas and methods, and the entire Chezhen Sag Es2 oil and gas exploration is of great realistic significance to enrich and develop Jiyang Depression subtle reservoir exploration technology, as in other similar areas from oil and gas exploration and guidance.