Based on the analysis of the formation of the residual oil in the area , combined with the fine geological and multidisciplinary research results, summed up the main types of remaining oil, combined with dynamic and static data, used some measures such as cyclic flooding, fracturing, profile control , to tap the potential of remaining oil, and achieved good results.

Through thirty years of development, Lianhua oil reservoir has entered into the stage of low-speed development. At present, the rate of oil production is only 0.0033%. Firstly, it divided development stage of Lianhua reservoir and analyzed production characteristics of each stage. By mean of the production decline curve, it predicted the recovery of the reservoir to estimate the ultimate recoverable reserves and the recovery percent. The results show that the ultimate recoverable reserves of Lianhua reservoir was about 50.813×104 t, the ultimate recovery was 13.177%, the recovery percent of recoverable reserves had reached up to 95.094%, and the remaining recoverable reserves were rare. Therefore, it urgently needs to find a more reasonable development model to do secondary development of Lianhua reservoir. The conclusions have an important realistic significance of guiding secondary development of the Lianhua reservoir.

S-16 block of YSL oilfield is fault lithologic deposit. For the practical problems of low permeability, high injection pressure causing to difficult injection and low degree of reserve recovery due to delaying the supplement of producing energy, this paper applies the module E300 of Eclipse to establishing the triaxiality and triphase compositional model of the simulated block which takes the 11Y67-611 and 11Y69-56 as the target wells, completing the numerical simulation study of optimizing parameters of CO2 huff and puff by using of the evaluation indexes of oil increment and the oil-draining rate. It provided theoretical reference for YSL oilfield to carry out CO2 huff and puff that its optimized parameters.

This paper analyzed the balanced flood performance of various layers and the remaining oil distribution through numerical simulation technique. It shows that, the main remaining oil type of intended layers is caused by voidage-injection imperfection. Considering the needs of the follow-up infill well pattern and tertiary oil recovery, we decide to maintain the relative independence and integrity of each well network without disturbing the pattern configuration and the mining exploit object of various sets of well pattern. Finally we confirm to perforate adding the first infill wells of intended layers to consummate the water flooding regime. Through analyzing the production target of different well pattern optimization programs relatively, it shows that the best program has regular well pattern and large drilled thickness.

For an oil well, when its water cut rises to a certain high point, the economical input gets equal to the economical output, at this time, this oil well produces nothing economically. If the water cut exceeds this point, then this oil well produces a deficit. This point is the so-called economical terminal water cut. Based on the theory of break even analysis, this paper determined the components of the cost of an oil well, analyzed the factors affecting the economical terminal water cut of oil well and developed a mathematical model to predict the value of economical terminal water cut.