Research On Leakage Prevention And Reservoir Protection Technology Of Horizontal Wells In Weihe Oilfield

In the exploration and development of oil in Jinghe oil field, often encountered lost circulation, such as Q4, ZhiDan group and Yanchang group appeared slight or serious lost circulation, uncovered the lack of effective reservoir in the process of reservoir protection. In order to effectively prevent lost circulation, improve the success rate of the plugging well lost, make sure to evaluate the accuracy and timeliness of the formation and improve oil production, carrying out this research. This study is elastic fracture mechanics finite element method to determine the wellbore drilling fluid column pressure changes with crack width changes, the object is achieved by computer simulation to find out the relationship between changes in crack width and the wellbore pressure, and the eventual establishment of crack width and wellbore pressure formation rock mechanics parameters and fracture length prediction model.Research combined with the well lost of the upper strata Q4, ZhiDan group of specific conditions, research has formed a technology, seam 1-6 mm wide bridge plugging formulation and construction technology, plugging pressure reaches 6 MPa. In view of the lost circulation purpose of layer formation, research has formed a protect reservoir acid soluble plugging system formula and its construction technology, prevented lost circulation system for seam width 200-300 um fracture has good prevented lost circulation effect, plugging rate can reach 100%, pressure can reach 8 MPa; Acid soluble plugging formula of 1-5 mm wide seam has good plugging effect, under pressure to achieve 6 MPa. When loss of judgmentad,such as lost in space for well lost, water layer, and so on, bridge plugging measures can not solve, formed the high water lose mud formulation and malignant well lost plugging. Because of reservoir shouted radius below 1 microns below, conventional treatment agent particle size is very difficult to achieve sealing requirement, by adding nano emulsion formation system in low porosity low permeability reservoir near the wall quickly form a dense block belt, block rate is above 99%, core permeability recovery rate of 87% on average, can prevent the invasion of solid phase, liquid phase deep reservoir formation damage. Related technologies in JH17P11 well, JH2-1 well and JH69P25 well has been successfully applied, effectively prevent the leakage, plugging success rate 100%, reservoir protection achieved significant effect.