The shallow, thin super-heavy oil reservoir demonstrates certain characteristics, such as shallow reservoir depths, low-formation temperature, and high crude oil viscosity at reservoir temperatures. In the current production process, the central area of P601 is undergoing high-frequency huff and puff operations, facing certain problems such as decreasing production, low recovery rates, and rapid depletion of formation pressure. Through physical simulation experiments, the various elements of HDNS-enhanced oil recovery technology were analyzed. Nitrogen plus an oil-soluble viscosity reducer can improve the thermal recovery and development effect of super-heavy oil. With the addition of the viscosity-reducing slug, the recovery rate of steam flooding was 58.61%, which was 23.32% higher than that of pure steam flooding; after adding the 0.8 PV nitrogen slug, the recovery rate increased to 76.48%. With the increased nitrogen injection dosage, the water breakthrough time was extended, the water cut decreased, and the recovery rate increased. Nitrogen also plays a role in profile control and plugging within the reservoir; this function can effectively increase the heating range, increase steam sweep efficiency, and reduce water cut. So, the synergistic effects of steam, nitrogen, and viscosity-reducing agents are good. This technology enhances the development of shallow-layer heavy oil reservoirs, and subsequent development technologies are being compared and studied to ensure the sustainable development of super-heavy oil reservoirs.

The Neoproterozoic Shawan Formation in the Chepaizi area is recognized for its significant heavy oil resources. Investigating the underlying causes and mechanisms of heavy oil changes in accordance with the specific characteristics of the reservoir is crucial for future exploration and development. The distribution of heavy oil in the Pai 612 block was identified to present a combination of shallow and thin deposits, high porosity, high permeability, and elevated water content. The physicochemical properties of the crude oil included a complex composition, high density, high viscosity, substantial gel content, and notable oxidation-biodegradation potential. The oxidation and biodegradation of crude oil during transportation played the critical roles in the formation of heavy oil. As cru3de oil was transported upward, the formation temperature decreased, resulting in increased viscosity. An excess of water could initially increase and subsequently decrease heavy oil viscosity, while groundwater in the reservoir contained various chemicals that interacted with colloids and asphaltenes, further increasing the viscosity. During the formation of the early heavy oil reservoir, the light oil was unable to dissolve and transport the high-molecular-weight asphaltene component, leading to the high resin content in the heavy oil of the Pai 612 block.