This paper will describe the successful application and effects of completely new Hydro mechanical Cleaning and Hydrodynamic Bearing profiles machined externally on drilling equipment to improve hole cleaning and reduce rotary friction. Qualification programmes, including initial proving trials on a test rig, computational fluid dynamics and cuttings transportation flow loop tests, will supplement details from successful field operational use of this equipment. Introduction Drilling for Oil and Gas has reached the stage where it is more economical to drill an extended reach well to exploit reservoirs on the periphery of existing developments. Similarly, long horizontal sections through the reservoir are now the norm. The initial response to this need for extended reach drilling was to install top drives, upgrade the mechanical integrity of the drill string, and introduce larger outside diameter drill pipe with better materials and stronger connections. These improvements have been integrated into well design and now the limits are the amount of rotary torque and hydraulic power available to rotate the drill string and circulate sufficient drilling fluid to clean the well. The initial challenge was to build a sub which would reduce rotary drilling torque while maintaining the integrity of the drill string. In the initial design of the low torque sub an experimental Hydro mechanical cleaning zone was added. This tool proved to be very successful, showing up to 40% reduction in rotary torque. More importantly, the operator noticed improvements in hole cleaning. These included cuttings appearing at surface in close to theoretical bottoms up time, an increase in the size of cuttings, reduced pick-up and slack-off weights and improved steerability. The success of the Hydro mechanical hole cleaning design led to the development of heavy weight drill pipe and standard drill pipe with this feature. A critical part of the design of this Hydro mechanical cleaning drill pipe is that the cleaning zone is supported off the bore wall and only comes into contact with fluid or loose cuttings sedimentation. Success with concurrent field trials and testing led to the further development of the features described above and the addition of a dual upset tool joint to provide five bearing areas, each coated with industry standard hard facing material to control friction and wear. The remainder of this paper will describe the design principles, numerical modelling, application on drilling equipment, cuttings transport flow loop tests and on-going field operations of this HydrocleanTM System. Design Principles & Effects of New Profile Design & Functional Principles. (see fig. 1). The profile is designed with two different zones, the Hydro mechanical cleaning zone (HCZ) and the hydrodynamic bearing zone (HBZ), which interact and provide the two basic effects of the profile; hole cleaning and reduction of friction factor between the bearing areas on the modified drilling equipment and the bore wall. By design principles, the geometry of the profile modifies the trajectory of flowing lines in the annular passage, at the rotational speed ?, and the variation of geometry for drilling fluid passage, (either in terms of passage area or a combination of channel angles through which drilling fluid is forced to flow). There are two different alterations of flowing line patterns corresponding to the two different zones of the profile, where there is a Hydro mechanical cleaning effect and a hydrodynamic bearing effect. In order to have a better understanding of the effects developed by the profiles, the following will firstly describe the principles of the geometry. Design & Functional Principles. (see fig. 1). The profile is designed with two different zones, the Hydro mechanical cleaning zone (HCZ) and the hydrodynamic bearing zone (HBZ), which interact and provide the two basic effects of the profile; hole cleaning and reduction of friction factor between the bearing areas on the modified drilling equipment and the bore wall. By design principles, the geometry of the profile modifies the trajectory of flowing lines in the annular passage, at the rotational speed ?, and the variation of geometry for drilling fluid passage, (either in terms of passage area or a combination of channel angles through which drilling fluid is forced to flow). There are two different alterations of flowing line patterns corresponding to the two different zones of the profile, where there is a Hydro mechanical cleaning effect and a hydrodynamic bearing effect. In order to have a better understanding of the effects developed by the profiles, the following will firstly describe the principles of the geometry.

An understanding of the formation is essential for effective drilling, casing and completion of oil and gas wells. Several methods and many tools are available to obtain information about the formation. Some of these tools collect or provide downhole data during the drilling process and are, therefore, termed measurement-while-drilling (MWD) tools. This paper describes a new MWD tool which records formation data during the drilling process. process. System hardware is described and its operation and rig impact outlined. A discussion of the theoretical implications of measuring formation data during the drilling process is presented. Field data are presented and compared with wireline data. From these data, excellent MWD log quality is demonstrated. MWD gamma ray logs are shown to have a superior bed resolution to those produced by wireline, for most cases, and the resistivity sensor, contained in the recording system, is demonstrated to be the most versatile MWD resistivity tool commercially available. It is seen from field history that recording formation data while drilling is a cost-effective and reliable method of obtaining formation information when compared to other available methods. Introduction A variety of MWD tools is commercially available which provide services ranging from only directional through multi-sensor packages which include various combinations of hole angle and direction, formation gamma and resistivity, and downhole temperature and pressure and weight and torque on bit. Except for the recording system discussed in this article, all commercial MWD systems depend on some form of mud-pulse telemetry for communication of the data from downhole to the surface. There are many cases when real time transfer of data is required. Tool face measurement during steering and WOB, for instance, would be of little use if not provided in real time. However, information obtained during drilling can provided in real time. However, information obtained during drilling can be of value when available at the completion of each bit run. Using this approach, a complex and costly portion of the MWD system can be eliminated, with concomitant advantages in cost, reliability and rig impact. Many applications do exist for recording formation characteristics (lithology) during the drilling process. A recording MWD service can be used when drilling surface hole to identify shallow hydrocarbons and eliminate a wireline log. High-angle and difficult holes are easily logged with a recording MWD tool when wireline logging is difficult, costly or impossible.

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