| As oil and gas exploration and development shift towards more complex areas and deeper formations, complex geological conditions bring many technical problems to drilling, especially slow ROP and long drill period. At the same time, with increasingly higher oil price, global E&P investment rapidly grows. From1990to2005, E&P investment increased by more than one time, more than half of which was drilling spending. Drilling engineering features concentrated funding, concentrated technologies, high investment and high risks, drilling level is very important to oil and gas E&P benefit. The result of research of world drilling technology development trend indicates that drilling real time optimization and remote monitoring technology is an important development direction of improving ROP technology. Although domestic improving ROP has acquired some results, further improving ROP lacks effective measures because drilling is full more and more difficulty and high-end technologies and equipments are dominated by foreign companies. In order to reduce drilling cost and increase E&P benefit, an simple practical, easily popularized and continuous excavated drilling parameter optimization and improving ROP method is needed.In this paper, based on investigating early specific energy optimization drilling technology present situations and existing problems, According to energy conservation principle and drilling engineering theory, VSI optimization drilling new method is proposed. By analyzing the fundamental of this technology, VSI optimization drilling theory model in different drilling modes is built by numerical simulation method. Simultaneously, this model considers the influence of water jet impact force. Bit hydraulic item is introduced to VSI model, which makes VSI model more closed to drilling real condition. According to different drilling conditions, VSI baseline definite method is built, which is determined mainly by rock strength calculation method and tentative drilling test method. The response features of bit balling, bit bluntness and bit vibration bottlenecks etc. are effectively analyzed by VSI curve and the influence of VSI on ROP and VSI change influence with drilling parameters are concluded. VSI optimization drilling technology improving ROP potential is further excavated and bit optimum seeking method based on micro-well section drilling specific energy and new bit abrasion forecast method are built, which basically solves the previous problem that specific energy technology was difficultly used to excellently seek bit types. Considering different demands, such as field application, indoor research and remote support etc., VSI optimization drilling technology software system for domestic oilfields is developed with WITSO data protocol. This software was tested in many wells of Hongtai Block in Tuha Oilfield. By linking on-site well log instruments, VSI value was real-time picked, which helped on-site engineers and operators optimize drilling parameters, prolong bit life and improve drill speed. The calculation result and case analyse shows that VSI optimization drilling technology could improve drilling efficiency, guide field engineers to identify bottleneck factors influencing drilling efficiency and help to gain improvement measures to maximize ROP. Simultaneously, by calculating drilled well log data and analyzing the change trend of VSI curve in different working conditions, scientific foundations are provided for drilling parameter effective optimization in the same block in the future. Field application practice proves that this software verify the accuracy of VSI model and the feasibility of drilling parameter optimization, which could effectively guide field drilling operations and this software could widely be popularized and applied. |
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