环状掺水工艺降温集输试验技术研究

A Study into Using Circular Water-blending Technology to Reduce Temperature and Gather and Transmit Oil and Gas

大庆油田外围低产、低渗透油藏原油集输物性差,油井产量低,单位产能建设投资高,集输能耗大。其中,油气集输环节分别由集油、脱水、原油稳定处理及储运能耗4部分组成。各部分中,集油部分的能耗更是占到集输系统总能耗的60%～80%,设法降低集油环节的能耗是集输流程节能的关键。对此,开展了确定安全混输温度界限的室内外试验,实现原油在凝固点附近安全运行。根据中高含水期油田开发的特点,对高产液、高含水的集油环开展不加热集输试验。试验区试验结果表明,原油含水率达到并超过转相点后,其流动阻力明显下降,有利于低温集输;对于部分产液量大于20t/d、含水率大于80%的集油环,可采取季节性停掺冷输工艺;对于长期低温运行的集油环出现的开井困难情况,可采取管线热洗、通球物理清洗,增加管道泵、混输泵或工艺改造等措施加以解决;对于污水处理反冲洗效果变差的情况,需要加强适合低温处理药剂的研究与应用。

Daqing Oilfield Company faces a series of challenges in developing the peripheral low-yield,low- permeability oil reservoirs of the Daqing oilfield ,which include poor crude collecting and transmission properties,low well output,high unit-capacity investment and high energy consumption during oil collecting and transmission.The oil and gas collecting and transmission system of these reservoirs consists of four parts -- oil collecting,dewatering,crude oil stabilizing treatment and storage and transmission energy consumption.The energy consumption in the oil collecting section represents 60%-80% of total energy consumption by the collecting and transmission system ;therefore ,reducing energy consumption for the oil collecting section is the key to saving energy in the collecting and transmission process.Researchers carried out outdoor experiments to identify the temperature range for safe transportation of different products in the same pipeline to enable safe crude operation near the freezing point.Having regard to the characteristics of oilfield development during high water-cut period,these researchers performed a collecting and transmission experiment without heating on high-liquid yield,high water-cut oil collecting tings.Experimental results show that crude oil＇s flow resistance reduces significantly after water cut reaches and passes the reverse phase point.This is instrumental to oil collecting and transmission at low temperatures.For those oil collecting rings with liquid yields exceeding 20t/d and water cut higher than 80% ,seasonal blending stopping and cold transmission technology could be used. Wells for oil collecting rings that have operated for a long time may be difficult to open and such measures as hot pipeline wash ,ball-passing physical wash ,addition of a pipe pump and a multiphase pump or technical upgrade could be taken.If the effect of back wash in sewage treatment becomes less satisfactory,the research and application of chemical agents suitable for low-temperature treatment should be strengthened.