Study On Horizontal Well Coiled-Tubing Multizone Fracturing Technology

The low-permeable reservoir will be the important resource base of increasing reserve and production in the petroleum industry in our country in a long term .Horizontal completed well combining with multizone fracturing is utilized as the most effective means to develop the low-permeable reservoir with the challenges of large filtration resistance, weak connectivity, low EOR and low well productivity. A safe and reliable multi-zone fracture technology for low-permeable reservoir is researched and developed in terms of horizontal well completion string, downhole control technology and fracturing process for horizontal well etc. It is very significant for improving hydraulic fracture process and development of low-permeable reservoir that multi-zone fracture technology for horizontal wellbore is researched and developed in this paper.The paper focus on follow areas:1、A new completion string is developed to be used for the low-permeable reservoir. The string utilizes two vital components: one is external casing packer (ECP) used for zonal isolation in horizontal wellbore and another is casing sliding-sleeve used to control flow from oil reservoir. Reservoir damage is avoided by means of the new technology instead of cementing and perforation.2、The mechanical model of completion string running is set up in terms of 2D/3D horizontal wellbore and geometry of completion tools. Based upon this model, the running performance could be validated and estimated effectively. The operation process for horizontal well completion is also researched in this paper.3、Multi-zone fracture for horizontal wellbore based on coiled tubing(CT) integrating the completion string with downhole control technology is researched and developed in this paper. More importantly, massive hydraulic fracturing and deep-well fracturing can be performed on the basis of this technology with advantages of lower operation risk, easy deployment and lower pressure loss.4、Downhole control technology for horizontal wellbore is developed in this paper. By means of casing sliding-sleeve, multi-zone fracture for horizontal wellbore is performed and some key problems are figured out, such as water location and water shut-off (WSO).5、The key completion tools and downhole control tools are designed, such as casing sliding-sleeve, hydraulic-actuated switch, rotating throttling washing tools, mechanical-actuated switch,pressure-regulated inflatble packer, one-way valve for horizontal well etc. It is proved by workbench test that all tools meet the demand and is available for field test. Four national patents of tools have been applied and licensed so far.