王信 1张民立 1王强 1庄伟 1章卫军 1王志彬 2李毅峰3
作者信息
- 1. 渤海钻探泥浆技术服务分公司,天津300280
- 2. 渤海钻探第三钻井分公司,天津300280
- 3. 青海油田公司采油五厂,甘肃敦煌736202
- 折叠
摘要
Abstract
Four blocks in the Qaidam Basin,Niudong,Lenghu,Zahaquan and Yingxi,have formation rocks with complex lithology,such as salt,gypsum,mirabilite,and hard and brittle shales etc.Downhole troubles have been frequently encountered in previous drilling operations.The Niudong nasal structure in the piedmont of the Altun Mountain in the basin,affected by the orogenesis,has overall formation dipping angles between 60° and 70°.High formation stress,high pressure saltwater and varied coefficients of pressure have resulted in frequent borehole wall instability in open hole section.A BH-WEI drilling fluid for the so-called "three high" (high pressure,high sulfide,and high risk area) wells,has been used in drilling 20 wells since 2013.To perform well in drilling fluid technical service,relevant data were investigated prior to drilling.Based on laboratory experiment and field practice,it was concluded that drilling fluid with low activity,strong plugging and inhibitive capacity was beneficial to borehole wall stability.Four key exploratory wells,the first multi-lateral horizontal well and the first horizontal well in Zahaquan have been completed,the maximum mud density used was 2.35 g/cm3,the average percentage of hole enlargement was 4.67％,and the ratio of successful wireline logging was 100％.The well Zaping-1 is the first horizontal well targeted with tight oil reservoir in Zahaquan.In the block Dongping,a four-interval horizontal well was drilled in 2013 with Weatherford's MEG drilling fluid.This well was not be able to drill to the designed depth because of severe mud losses and other downhole troubles.Using the BH-WEI drilling fluid,six horizontal wells were completed successfully in 2013-2014 in the same block,and no downhole trouble has been encountered throughout the drilling operations.Two horizontal wells,Ping-1H-2-1 and Ping-1 H-2-2,put into production in 2014,were both high production rate wells in the same block;the average daily gas production rate was 50× 104 m3/d.Field application has shown that the BH-WEI drilling fluid had simple formulation,and the mud properties were thus easy to maintain.The BH-WEI drilling fluid had good shear thinning property,high YP/PV ratio,low plastic viscosity,low pressure loss in annular space,good hole cleaning performance and good lubricity and inhibitive capacity.Using this drilling fluid,borehole collapse in drilling the dark gray Jurassic mudstone,inability to exert WOB in horizontal drilling and differential pipe sticking were avoided.To concluded,the BH-WEI drilling fluid is a unique drilling fluid suitable for use in drilling exploratory well and horizontal well in the troublesome drilling areas in Qinghai oilfield.关键词
井壁稳定/高压盐水层/有机盐钻井液/抗三高水基钻井液/低活度/封堵/防止地层损害/柴达木盆地Key words
Borehole wall stabilization/High pressure saltwater zone/Organic salt drilling fluid/Water base drilling fluid for "three high" well/Low activity/Plugging/Formation damage prevention/Qaidam Basin分类
能源科技
