GW-CP194-80A型保压取心工具的研制

保压取心技术可以使取出的岩心保持在原始地层压力状态下,能最大限度地减少岩心中油气等组分的损失,进而准确求取井底条件下储层流体饱和度等重要地层参数,是目前最先进且技术难度最高的钻井取心技术。但是,较之于国外同类产品,国内现有的保压取心工具在岩心直径和保压能力两项主要技术指标方面尚存在着明显的差距,尤其是在保压能力方面,难以满足深海钻探、陆上深井和水平井保压取心作业的需求,限制了该技术的应用范围和普及率。为此,基于已有的GWY194-70BB型保压取心工具,设计研发了GW-CP194-80A型起钻式保压取心工具(以下简称新工具)。现场应用效果表明:①通过采用可受控转动的大通径球阀密封装置和高强度保压内筒,新工具所取岩心直径由原来的70 mm提升到80 mm、额定保压能力由原来的20 MPa提升到60 MPa;②新工具的内提式差动总成和上下同步密封机构,有效地解决了大斜度井、水平井取心作业过程中球阀关闭、保压成功率低的难题;③新工具共应用于现场5口井27筒次,取心平均收获率为87.5%、保压成功率达92.6%。结论认为,新工具达到了岩心直径和保压能力的设计目标,满足了深海、深层、非常规油气藏保压取心作业的需求,可为常规及非常规油气藏的储层评价、增产改造等提供技术支撑。

Development and application of GW-CP194-80A pressure-maintaining coring tool

Pressure-maintaining coring technology can reduce the loss of hydrocarbon compositions in cores to the uttermost while keeping the cores in the state of original formation pressure, so as to obtain important formation parameters under the conditions of bottom hole, e.g. reservoir fluid saturation. At present, it is the most advanced coring technology with the highest technical difficulty. Compared with foreign similar technical products, however, there is an obvious gap between the domestic existing pressure-maintaining coring tools in two main technical indexes, i.e. core diameter and pressure maintaining capacity. And especially in the aspect of pressure maintaining capacity, domestic products can hardly meet the needs of pressure-maintaining coring operations in deep sea drilling, onshore deep wells and horizontal wells, which limits its application scope and popularity rate. In this paper, GW-CP194-80A tripping-out pressure-maintaining coring tool (hereinafter, "new tool" for short) was designed and developed on the basis of GWY194-70BB pressure-maintaining coring tool. And the following field application results were obtained. First, the diameter of the core taken by the new tool is increased from 70 mm to 80 mm, and the rated pressure maintaining capacity is increased from 20 MPa to 60 MPa by adopting the large-diameter ball valve sealing device of controllable rotation and the high-strength pressure-maintaining inner cylinder. Second, internal-lift differential assembly and upper–lower synchronous sealing mechanism in the new tool effectively solve the closing problem of ball valves and increase the success rate of pressure maintaining in the coring process of high inclination wells and horizontal wells. Third, during the field application of the new tool in 5 wells by 27 barrel times, the average core recovery rate is 87.5% and the success rate of pressure maintaining is 92.6%. In conclusion, the new tool can reach the design target of core diameter and pressure maintaining capacity, meet the needs of pressure maintaining coring in deep sea, deep seated and unconventional oil and gas reservoirs, and provide technical support for the reservoir evaluation and stimulation of conventional and unconventional oil and gas reservoirs.