The fuzzy ball drilling fluids have been developed on the basis of the circulation foam and Aphron to control lost circulation effectively. There are some difficulties in drilling U-type well, such as well-bore stability, cutting carrying problem, large torque and friction at the horizontal section, and formation damage to coal-bed. The objective of this paper was to show some applications of fuzzy ball drilling fluids on U-type wells of the Ordos Basin and prove the superiority of fuzzy ball drilling fluid in CBM drilling. To the three mentioned cases, the density of fuzzy ball drilling fluid was 0.90~1.18g/cm3, the funnel viscosity was 45~72s, the dynamic shear force was 12~19 Pa, the PV was 13~19mPa·s and the pH was ranged from 7 to 9. To use the fuzzy ball drilling fluids, the average ROP increased above 10% with no borehole complexity, such as stuck pipe, hole enlargement causing poor cleaning and etc. These cases reflected excellent properties of the fuzzy ball drilling fluids including effectively sealing, good carrying and suspension ability, formation damage control and compatible weighted by inert materials. Furthermore, the fuzzy ball drilling fluids will not affect BHA tools like motors and MWD in CBM drilling.
Fuzzy ball material which imitating the structure of bacteria have been tested and developed as a new lost circulation material. The fuzzy plugging theory include three pressure distribution methods: the pressure decomposition filling mechanism, the pressure reducing filling mechanism and the pressure support filling mechanism. Fuzzy ball material relies on its own particular structure, achieving full-size sealing and self-adjustment to match the porous media. Fuzzy ball working fluids can be prepared without auxiliary equipment and its non-weighted density is 0.85~1.0g/cm3. Its density can be up to 1.2g/cm3 when it is weighted by inert materials to meet the need of near/under balanced drilling. Indoor test showed that novel working fluids have significant inhibitive capacity and sealing characteristic. There are three properties of fuzzy three ball working fluids: inhibitive capacity, anti-temperature capacity and sealing characteristic. Fuzzy ball working fluid has been successful applied in hundreds of wells to solve the problems such as collapse, severe losses and etc.
Fuzzy ball drilling fluids have been developed in order to effectively control lost circulation during CBM drilling. Depending upon fuzzy balls and colloids in fuzzy balls, the fuzzy ball drilling fluids changed their shapes and properties to completely plug underground heterogeneous seepage channels so as to strengthen the pressure bearing capacity of formations. This paper describes the available features of the fuzzy ball drilling fluid including efficient plugging, good carrying and suspension, formation damage control, compatible weighted by any weighted materials without auxiliary equipment. The fuzzy ball drilling fluids can finish drilling in low pressure natural gas zone, control CBM leakage; control the natural fractures, drilling in different pressures in the same open hole, combination with the air drilling mode, etc. during Ordos CBM drilling. The fuzzy ball drilling fluid will not affect down-hole motors and MWD. The fuzzy ball drilling fluid will be blend simply as conventional water based drilling fluids. The existing CBM drilling equipment can completely meet the fuzzy ball drilling mixing and it is maintained conveniently. The fuzzy ball drilling fluid is the efficient drilling fluid.
the risk evaluation indicator system by enterprise resource planning (ERP) system is characterized by excessive subjectivity, lack of reasonable basis for establishing, and redundancy. The paper adopts the rough set theory, proposes attribute reduction algorithm based on information entropy, and makes attribute reduction on risk control indicators for implementation of ERP system by integrating cases from 10 enterprises that have already implemented ERP systems. The resultsshow that attribute reduction algorithm based on rough set is effective and available on reduction of risk control indicator for implementation of ERP system.
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