Abstract: In recent years, Jilin oilfield invests 9.5 billion yuan for the productivity construction of one million tons in the new areas, and the output-to-input ratio of conventaionl refracturing in old areas is less than 1.0, and profitable productivity construction and stable prodution becomre more and more difficult due to the dual effect of its basic geological characteristics (low permeability and low abundance) and low oil price. In order to deal with these challenges and realize low-cost efficient development in Jilin oilfield, the new connotation of geology-engineering integration with the techncial concept of "large fracturing" as the core was proposed, and then a series of technological research and field test were carried out in low permeability oilfields, e.g. Xinli oilfield. The new connotation of geology-engineering integration is embodied as follows. First, according to the engineering and technological requirements, the data of the block is acquired and recognized again, including stratified yield, hydroscopicity, pressure, fracure azimuth and the stress of reservoir and barrier, so that the project design will be more targeted. Second, according to the fracturing technology and construction requirements, the well structure and surface location of the wells are reoptimized and the number of drilling platforms are optimized so as to minimize the total productivity construction investment. Third, based on previous geological recognition and drilling optimization, a series of fracturing technologies with "turnaround fracturing, energized fracturing, plugging contorl fracturing and interference fracturing" as the main parts are developed. And fourth, a series of supporting technologies are innovated, including oil production, water injection, surface engineering and Internet of Things, to reduce the disposable investment and cut down the operation cost. This technological mode is applied to the productivity construction of new areas (e.g. No.3 platform in block Ⅲ) and the potential tapping of old areas (e.g. the middle area of block VI), and the application results are remarkable. Compared with the main area, No.3 platform is 40% higher in initial production, 57% higher in stable production, 8.2% higher in return rate and 16% lower in productivity construciton investment of one million tons. After fracturing is carried out in the middle of block VI, the single-well cumulative oil increment is over 400 t in the commissioning period of 16 months, its stimulation result is 4 times of the conventional fracturing result, and the output-to-input ratio is higher than 2.0. It is practically indicated that the integrated geology and enginnering mode with the engineering as the core is currently the effective way to solve the difficulty of profitable development in the low permeability oilfields whose geological situations are understood more definitely.

Key words: geology-engineering integration, low permeability oilfield, fracturing stimulation, low-cost engineering technology