Research On The Prediction Method Of Development Index Of Ultra-short Radius Horizontal Wells

With the continued development of oil fields and the frequent operation of old oil region,the situration of wells becomes worsening, besides the reservoir heterogeneity, all of thesebadly influence the recovery of the reservoir. If we drill new wells or interspaced wells in thedevelopment area, the period of drilling wells is long and the cost is large. Side-trackingultra-short radius horizontal wells in the inner side of the drivepipe not only can save the costof the drilling wells, but also can increase the exposed area of the oil zones, enhance oilrecovery and economic benefit.This paper is based on the numerical simulation of the test region for the ultra-short radiushorizontal wells where lies in the Duan Xi. On the basis of history matching, evaluated thedistribution of remaining oil, then analysised the sensitity of the infuential factors of thedevelopment effects. On this basis, by orthogonal numerical simulation program design, theauthor calculates quantitatively10-year cumulative oil production after side-tracking, anduses multiple regression method to establish a relation between10-year cumulative oilproduction and the effective thickness, the dimensionless height from the top, the distancebetween oil wells and water wells, the average permeability, the average residual oilsaturation and the degree of perfection in the recovery process of horizontal wells, besidescombines with breakeven analysis, then determines technical limits of ultra-short radius zoneselection, such as the effective thickness, the distance between oil wells and water wells, theaverage residual oil saturation, dimensionless height from the top, finally draws a plate. Thenestablished the prediction method of development index of ultra-short radius horizontal wellsand put forward the technical and economic limit of ultra-short radius side-tracking horizontalwells. Finally, based on the established technical and economic limit, selected the potentialwells and layers of the ultra-short radius horizontal wells in the numerical simulation area ofDuan Xi.