Optimization Designs On Controlling Water Fracturing In Low Permeability Reservoirs

The Chang2reservoirs of JY area are low porosity and low permeability,and have thelow natural production capacity or no natural production capacity,so the commercial oil andgas flow is able to obtain by hydraulic fracturing,however, the bottom water of the reservoirsare development, the improper fracturing usually cause water production only in oil well orthe moisture content is higher after fracturing. Therefore this article through to theunderstanding of the basic geological characteristics of reservoir in the area, after the analysisof reservoir pressure in the study area of the main causes of water production, based on thestudy area to select fracturing technique, optimization of fracturing parameters, field testshow that good fracturing effect is obtained. This article’s main research results and mainlyknown is as follows:(1)The reservoirs of JY area are low porosity,low permeability and poor thinreservoirs.The vertical distribution of oily water is that oil layers,oil-water layers,water layersand dry layers are interweaved with one another.The oil-water differentiation is poor invertical direction,and the reservoir of Chang2is bottom water reservoir.So the need ofcontrol fracture height is for the reservoirs in hydraulic fracturing.(2)According to the present technical conditions,this article proposes that it is toprimarily control the crack to extend downward,and secondarily control the crack to extendupward on the basis of the reservoir conditions,which making the goal achieve the bestfracturing effect,and the controlling water fracturing of variable displacement multistagebackfills is the most suitable for the reservoir in the study area.(3)Because of not taking full account of the actual situation of the reservoirs,and notcarring out scientific and reasonable design,the ranges of the former constructiondisplacement, pad fluid,sand-carrier fluid and sand (adding sand intensity) are so broad in thestudy area. At the same time,the phenomenon such as the using volume of the displacingliquid is higher than the designing volume and the perforated degree is so big,is biggestproblem of fracturing construction at present in the study area reservoir.(4) The optimized controlling water fracturing parameters is obtained by using threedimensional fracturing simulation software FracproPT10.3, that is, a. Optimization of fracture length: optimization result of fracture length in Chang2reservoir is about60m;b.Optimization of dimensionless flow conductivity: dimensionless flow conductivity FCDin Chang2reservoir is1.8~9.c. Optimization of perforation parameters:①perforation orientation:0°to30°;②gun type of the perforating:127;③hole density of the perforating:16hole/m;④porediameter of the perforating:1cm;⑤perforated degree:15%~45%, and the perforationposition should be located at the top;d. Optimization of the sand volume and sand strength: sand volume is3m3~15m3inChang2reservoir, sand strength is0.7m3/m~1.0m3/m; sand-carrier fluid volume is23m3~67m3;e. Optimization of construction displacement: displacement optimization is in0.8m3/min to1.4m3/min in Chang2reservoir.f. Optimization of prepad fluid percentage: the percentage of prepad fluid should becontrolled at about25%in Chang2reservoir;g. Optimization of volume of the displacing liquid: displacement fluid volume is5.7m3~5.9m3in Chang2reservoir;h.Optimization of ways of adding sand: ways of adding sand is10%~20%~15%~25%~35%~35%~30%~35%in Chang2reservoir.(5) The technology are good practical effect on the spot, production have significantlyincreased after fracturing.