Quantitative Evaluation of the Lateral Sealing Ability of Normal Faults in Siliciclastic Sequences: Implication for Fault Trap in Well Gang 64, in the West Qikou Sag, China

Abstract

The lateral sealing ability of a normal fault is a major factor in creating hydrocarbon traps. Therefore, a methodology for assessing the sealing ability of faults in the siliciclastic sequences of subsidence basins has been established; moreover, by using this methodology, the uncertainty inherent in hydrocarbon exploration can be decreased. Moreover, the petrophysical properties of fault rocks and reservoirs are emphasized by the methodology. In addition, the petrophysical properties of fault rocks and reservoirs are mainly determined based on clay contents and compaction pressure according to experiments on manmade rock samples which are representative of the researching area. Furthermore, by using this methodology, the petrophysical properties of fault rocks and reservoirs, which are mainly determined based on clay content and compaction pressure according to experiments on manmade rock samples representative of the researching area are emphasized. Thus, the lateral sealing ability of the fault can be assessed as follows: First, a best-fit equation describing the displacement pressures, clay contents, and compaction pressures of the rock samples is established by us. Then, the positive pressure on the fault plane from the decomposition of effective overburden pressure is calculated; afterwards, the clay content of the fault rock (Shale Gouge Ratio) is calculated by us. Finally, the displacement pressures of the fault rock and the juxtaposed reservoir rock are predicted. Ultimately, based on this study which has been carried out, the results for the case study of the Tangjiahe fault in Well Gang 64, in the western part of the Qikou Sag, China coincide with the exploration results, which this coincidence confirms that this methodology is capable of evaluating the lateral sealing ability of faults in certain geologic settings.

Keywords

• normal fault
• lateral fault sealing
• siliciclastic sequences
• fault rock
• displacement pressure