Geometrical Modeling And Tectonic Interpretation Of Sancha Formation In Yunan Plant Structure

The Sanchaping structure is located at the Yun’anchang structure belt within the Eastern Sichuan steep structural belts. It is comprised of steep folds and faults with complex deformation. Many wells and surveys improved that the Eastern Sichuan structural belts reserve rich oil and gas. As a result, the main aim of this paper is to develop reasonable structure models and structural interpretations for oil and gas evaluation.Based on the previous studies, the modern geological structural theories and fault related folding theories, we analyzed the seismic sections of the Sanchaping structure, and constructed its three-dimensional models using geometric analysis by balanced geologic section and forward modeling combined with outcrop data. Our research illustrate that,The deformation of the eastern Sanchaping structure is controlled by the Daba Mountain. It is composed of the E-W Yun’ anchang structure and Dongcun structure. However, at the west, with the gradually resistance of the Daba Mountain’s disappear, the Sanchaping structure is gradually converted to the NE-SW Bayang structure. Our field structural investigation indicates that the Yun’ anchang-Bayang structure is a closed anticline with steep and upright limb.In the eastern Sanchaping structure, the main faults of the E-W extending Yunanchang and Dongcun structure thrust from south to north, meanwhile, backward thrust fault also developed at the eastern Sanchaping structure, and the forward and backward thrust fault induced pop-up structures forming high and steep anticline. However, the main fault of the Dongcun structure in the western Sanchaping thrust from north to south, forming imbricated structures. In general, the Sanchaping structure is a fault propagation fold with upright forelimb, and gentle back limb, while the imbricated structures system has a high and steep morphology. Furthermore, drilling data at the top of fault propagation fold also shows that the thickness of the core is normal, but forelimb is thicker.There is a reversed link between the deep main fault of Bayang structure and Yun anchang structure, our3D model shows the main fault of Yun’ anchang structure was cut by the main fault of the Bayang structure.