The Cement Slurry Inflating External Casing Packer Technology and Its Applications

Abstract

Lot's of well-completion challenges face operators to exploit comprehensive reservoirs and old oil field, such as interzonal channeling, up water and bottom water etc. The conventional well completion ways can't solve them effectively. For example, cementing method couldn't isolate well for the short interval between layers, otherwise it will contaminate the reservoir, and normal inflating External Casing Packer (ECP) method couldn't do well for its short life downhole and low isolation pressure. Recent advances in one of the old well-completion ways, namely Cement Slurry Inflating External Casing Packer (CSIECP) technology, will play a key role in meeting these challenges. This significant technological breakthrough made it possible to inflate several ECPs with cement slurry in one well profile. The CSIECP technology provides permanent and dependable isolation between layers because cement slurry will solidify to be cement stone. So this technology will benefit for producing and later stimulating operation, avoid cement slurry contaminating the reservoir, and raise output. The Drilling Technology Research Institute of Shengli Oil Field studies this technology and puts it into application firstly in 2002, P.R.China. The technology consists of three key techniques: special tools, high quality cement slurry and advanced process. This paper will give them detailed description including their properties and results of large-scale testing. In addition to a description of the technology research, the paper will present applications of CSIECP technology in Shengli Oil Field. Some are used to seal thin layer channeling, and some are used as isolation for stimulating operation and producing apart. More than twenty wells' applications show how this significant technological breakthrough provides cost-effective solutions to several completion problems that have loomed as obstacles to comprehensive reservoir exploitation. The CSIECP technology is not only an important technical measure to develop thin-bed reservoir, but also one of the effective well completion technologies for extended-reach and horizontal well. It has great economic and social benefits. Introduction The favorable flow condition is built between oil well and oil reservoir though well completion. It can isolate the oil, gas and water layer in well bore and achieve a sound operation on the oil well and a sound production of the oil well. If the annular space cann't be isolated completely, interzonal channeling will take place, which will affect the productivity of oil reservoir and even lead to oil well abandonment. The solution of well completion technique is an important measure to raise the production life of oil well, increase the recovery efficiency of oil reservoir and raise the benefit of oil-field development. The CSIECP technology is an advanced well completion technique based on conventional hydraulic inflating (such as water, drilling fluid and so on) packer technology. The process is to design firstly the number of ECPs and the setting location according to the geologic condition, then to hang the serial connection on the liner with liner hanger in well, and at last, the special cement slurry with fine fluidity and long solidification time will be used to inflate ECPs permanently so as to isolate effectively various layers (the structure of well completion string is shown in Fig.1). The technology consists of three key techniques: special tools, high quality cement slurry and advanced process. The detailed descriptions are as follows: 1. Tool technique The tool technology includes CSIECP and inner working string tool. The CSIECP used in this technology is composed of spindle, expansible rubber element and a set of pressure control valve system (The structure of ECP is shown in Fig.2). Work principle: high-pressure cement slurry pour in the cavity between expansible rubber element and spindle through pressure control valve system, then expansible rubber element swells to the outside of spindle so as to isolate the layers above and below the packer. When the internal pressure of expansible rubber element reaches a certain value, valve hole is closed permanently. After cement slurry solidifies, the strong isolation body will be formed.

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“…Pneumatic packers have often been cited for poor reliability, particularly for extended deployments [8]. Cement inflations can improve the reliability of pneumatic packers, but at the expense of retrievability [9]. While mechanical set packers have good reliability, the mechanical operation mechanism precludes incorporation of control lines.…”