The development effect of water flooding in an ultra-low permeability reservoir is poor due to its poor physical properties and high shale content, so an experimental study of air flooding which helps to complement energy production was carried out. Based on the Accelerating Rate Calorimeter experimental results, the crude oil of N block in L oilfield can undergo low-temperature oxidation reactions, which are the basic condition for air flooding. Three groups of experimental natural cylinder cores designed for oil displacement, water flooding and air flooding were used respectively, and the relationship between differential pressure, oil recovery, injection capacity with injection volume was investigated. It is observed that the recovery efficiency increased 2.58%, the injection-production pressure difference dropped 60% and the injection capability increased 60% in the experiment of shifting air flooding after water flooding to 75% moisture content, compared with water flooding alone. It has been shown in the results that the recovery efficiency improved sharply more than water flooding, the effect of depressurization and augmented injection was obvious, and the air displacement was thus validated. We suggest that other science and technology workers should perform further tests and verify this result through numerical simulation.

Accurately predicting oilfield development indicators (such as oil production, liquid production, current formation pressure, water cut, oil production rate, recovery rate, cost, profit, etc.) is to realize the rational and scientific development of oilfields, which is an important basis to ensure the stable production of the oilfield. Due to existing oilfield development index prediction methods being difficult to accurately reflect the complex nonlinear problem in the oil field development process, using the artificial neural network, which can predict the oilfield development index with the function of infinitely close to any non-linear function, will be the most ideal prediction method at present. This article summarizes four commonly used artificial neural networks: the BP neural network, the radial basis neural network, the generalized regression neural network, and the wavelet neural network, and mainly introduces their network structure, function types, calculation process and prediction results. Four kinds of artificial neural networks are optimized through various intelligent algorithms, and the principle and essence of optimization are analyzed. Furthermore, the advantages and disadvantages of the four artificial neural networks are summarized and compared. Finally, based on the application of artificial neural networks in other fields and on existing problems, a future development direction is proposed which can serve as a reference and guide for the research on accurate prediction of oilfield development indicators.

The Nadanhada terrain is the most typical terrain in Northeast China. It is located on the West Bank of the Wusuli River in the east of Heilongjiang Province. The division of tectonic units in Nadanhada area includes five stages: geosynclinal fold zone, Mesozoic subduction zone around the Pacific Ocean, back-arc marginal sea, orogenic belt and terrain formed by the closure of forearc basin, and so on. During the Mesozoic, the northeastern China was affected by the Mongolia-Okhotsk Ocean closure and the subduction of the Paleo-Pacific Ocean, and a large-scale tectono-magmatic activity took place. At the same time, the Nadanhada terrane drifted from low latitudes and eventually grew on the eastern side of the Jiamusi massif. Therefore, the Nadanhada terrane was formed in an oceanic environment. During the Mesozoic, it was situated on the continental margin of East Asia and formed terrigenous turbidite at the trench. At the same time, it underwent continuous subduction and local accretion, and finally formed a complete sedimentary sequence including oceanic siliceous rocks and terrigenous melanges. The direction of the tectonic line of the Nadanhada terrane changes from north to south, from NNE to NNW, and then to NW, showing an arc structure protruding westward. The direction of the present tectonic line can not represent the direction of its formation. It is the direction after the transformation of Dunmi fault left-lateral strike-slip activity and Sikhot-Alin region whole rotation.

The Nadanhada terrane is basically a large tectonic sedimentary hybrid, which is an accretionary complex belt formed by the subduction of the Pacific plate to the Eurasian plate. Through field geological survey, paleomagnetic analysis, paleontological analysis and microscopic observation of core slices, its structural and petrological characteristics were studied. The results show that the accretionary complex is mainly composed of 7 parts, including undeformed sedimentary rocks, shear deformed sedimentary rocks, shear deformed volcanic rocks, turbidites, deformed siliceous rocks, limestone blocks and basic ultrabasic rocks. Shear deformation structures of deformed sedimentary rocks and volcanic rocks are developed. The sediment grain size of the Lower Cretaceous reservoirs in each basin in the northern region is relatively coarse, the sorting is moderately deviated, and the rounding is poor, mainly secondary to angular. The grain size of the lower Cretaceous sediments of each basin in the southern region is relatively fine, with coarse, medium and fine sandstones, but mainly medium fine sandstones, with medium sorting preference and sub angular to sub round roundness.

The Nadanhada terrane is the most developed area of Mesozoic marine strata in eastern China. The migration process of the Nadanhada terrane is restored from two aspects of Palaeomagnetism and biopalaeogeography. It is concluded that the subduction of the oceanic plate to the continental margin of East Asia is accompanied by the strong deformation of the sedimentary cover during the growth of the Nadanhada terrane. Under the continuous compressive force generated by the subduction of the oceanic plate to the continental margin of East Asia, accretionary wedges continue to form in the direction of oceanic basin. At the same time, large detachment planes gradually form between accretionary complex and the basement of the Jiamusi massif. The evolution history of the Nadanhada terrane can be divided into five stages: the drift stage, the accretion stage of the continental margin, the bending stage of the terrane structural line, the compression stage of the terrane and the anticlockwise rotation stage of the terrane. Bijin terrane can be seen as the extension of Nadanhada terrane in NNE direction.