Abstract: The conditions of some wells in Zhongyuan oilfield are complex with a long treatment interval, small mono-layer thickness and great in-situ stress difference in vertical profile. It is difficult to stimulate the whole target interval by general hydraulically fracturing technique. In this paper, a set of layering
and chosen fracturing technique was developed, which included evaluation technique of target formation, tools of mechanical separating-layer. The technique was proven to be successful and effective in Zhongyuan oilfield because of outstanding stimulation effect.

Key words: Zhongyuan oilfield, hydraulic fracturing, sepa-rate-layer fracturing, fracturing string