Research On Fracturing Technology Of Chang 8 Reservoir In Yanchang Formation In ZW Area

In this paper,by studying the "four characteristics" of the Yanchang Formation in the ZW area,the reservoirs are finely classified.The optimization of perforation position,fracturing mode and construction parameters is strengthened by combining the geological characteristics of each type of reservoir,and the construction transformation before putting into production provides effective technical support for the exploration and development work in the ZW area,in order to the sustainable and stable development of the oil area.The main research method used in this paper is to evaluate the performance of fracturing fluids in the field and the pre-acid formula system based on the geological characteristics of the low-permeability sandstone reservoirs fracturing in the ZW area,combining with laboratory experiments.And new processes such as volume fracturing,multi-stage sand fracturing,hydraulic jet fracturing and pre-acid fracturing are studied.What's more,the different kinds of fracturing and transformation processes,construction parameters and design of different reservoirs are optimized.what's the most important,the key links of fracturing construction quality monitoring are put forward.The research has achieved the following results:1.The fracturing fluid formula is 0.25% CJ2-6+0.5%CF-5c+0.5% COP-1+0.1%TA-2+0.1%CJSJ-2.In view of the high filler content of the study area reservoir(average 15%)and the characteristics of reservoir in weak acid sensitivity,the pre-acid sand frac turing process is used,which uses the acid to dissolve filler content in the sandstone pore and throat.So that the conditions of reservoir seepage and oil and gas production capacity are improved;The two optimized acid solutions are as follows:12.0% hydrochloric acid + 4.0% hydrofluoric acid + 1.0% corrosion inhibitor + 0.5% demulsification drainage aid + 0.3% clay stabilizer.2.Reconstruction and parameter recommendation for the Chang 8 reservoir of the study area: for the type I reservoir(layer thickness of above 5 meters,the resistivity of 15?.m,acoustic time difference of greater than 230?m / s),mainly control the transformation strength,The opening degree of the upper perforation is below 20%.It is recommended sand amount of 5~15 cubic meters,the displacement of 1.0~1.4m3/min,sand ratio of 25%;type II reservoir(the layer thickness of above 8~25m,resistivity of more than 20?.m,sonic time difference of 220?m /s)has no obvious bottom water,which shows that the reservoir has poor physical properties,the interlayer is not developed and the shale content is higher.So it mainly suggests to increase the strengt h of the transformation,pre-acid fracturing,perforating in the middle and upper,it is recommended to add sand strength of 1.6 ~ 2.5 cubic meters,displacement of 1.8 ~2.2 cubic meters / min,sand ratio of 30%;Class III reservoir(layer thickness of abo ve 15 meters,the resistivity of above 15 ?·m,and the acoustic wave time difference of 215 to 230 ?m/s.Mainly using internal partial pressure or hydraulic jet fracturing,pre-acid fracturing,perforating in favorable parts of oil layer,it is recommended to add sand strength of 2.5 cubic meters,displacement of 2.0~2.4 cubic meters/min and sand ratio of 35%.