This paper describes a new approach to evaluating the effectiveness of the rotary steerable system (RSS) steering mechanism on wellbore tortuosity in horizontal wells. Wellbore tortuosity in drilling applications is defined as any unwanted deviation from the planned well trajectory. As reservoir objectives become more complex and exact, operators increasingly perceive the wellbore tortuosity as a serious concern in the process of drilling, completing, and producing wells. More than 700 wells were reviewed and analyzed in this study. Strict criteria were set during the classification process; the studied wells have a common geology and trajectory, and they use a very similar bottomhole assembly (BHA) design. The inclination values from the wireline tool are used to illustrate the attainable benefits in terms of wellbore quality and measure wellbore tortuosity. In addition, the wireline inclination data are compared with the actual measurement-while-drilling (MWD) survey to highlight the existence of the micro-dogleg severity (DLS) that cannot be measured by standard surveys. Due to the theoretical differences in the steering mechanism between the various types of RSS, it has been claimed that utilizing one steering mechanism over another can produce a less-tortuous wellbore. These steering mechanisms have previously been classified as either push-the-bit or point-the-bit mechanisms. The relative merits of a push-the-bit steering mechanism vs. a point-the-bit steering mechanism is an over-simplification; neither mechanism can deliver the premium wellbore quality the industry demands from RSS. The present study introduces the continuous proportional steering method (CPSM), and demonstrates how this mechanism can provide superior wellbore quality by reducing wellbore tortuosity. In addition, a superior inclination hold performance is observed in horizontal sections drilled with the CPSM. Curve intervals are more continuous and smoothly drilled through the planned directional changes. The research becomes a useful reference to analyze the performance and efficiency of RSS steering mechanisms across drilling and workover operations. Directional drilling service companies are encouraged and challenged to improve the efficiency and accuracy of RSS mechanisms, improving the hole quality and reducing micro-doglegs.

In the present paper, directional drilling job failures were carefully analyzed for the period 2014 and 2015 in wells drilled in the Kingdom of Saudi Arabia. The focus of the study was to evaluate the performance and efficiency of the Positive Displacement Motors (PDM) and Rotary Steerable Systems (RSS) during drilling operations. The data was collected from Saudi Aramco database and limited to wells that used PDM and RSS as a directional drilling system. A total of 7772 runs were reviewed and the information was classified according to tool size, number of runs, operating time, lost time, number of failures and hole size. A detailed and comprehensive study was conducted individually for each run that a PDM and RSS was used, reviewing daily drilling reports and analyzing the performance and efficiency of the PDM and RSS in drilling operations across the Kingdom of Saudi Arabia. Focusing on PDM failures, it was observed that 45.41% of the problems occurred before 50 hours of operating time. In the case of RSS, the study revealed that 49.59% of the failures occurred before 50 hours of operating time. The causes of the failures were a combination of different factors such as vibration, temperature, type of drilling fluids used and reservoir properties such as H2S and CO2 content. The PDM average operating time remained almost the same (77 hours to 78 hours from 2014 to 2015), moreover the efficiency improved from 95.37% to 96.94% (1.64% improvement). The RSS average operating time dropped from 103 hours to 97 hours from 2014 to 2015, a reduction of 5.83%. The efficiency improved from 88.78% to 90.83% (2.30% improvement). The study concluded that the reduction of the operating time can lead to a higher efficiency on the PDM and RSS and this can be achieved by replacing these tools on every trip and performing preventive maintenance after each run. Also, improving the drilling parameters and durability of the directional drilling system will improve their performance and efficiency. The research became a useful reference to analyze the performance and efficiency of PDM and RSS Systems across Saudi Arabia's drilling operations. Directional Drilling Service Companies are encouraged and challenged to improve the performance, efficiency, and durability of their drilling tools.

This paper describes a new approach to evaluating the effectiveness of the rotary steerable system (RSS) steering mechanism on wellbore tortuosity in horizontal wells. Wellbore tortuosity in drilling applications is defined as any unwanted deviation from the planned well trajectory. As reservoir objectives become more complex and exact, operators increasingly perceive the wellbore tortuosity as a serious concern in the process of drilling, completing, and producing wells. Strict criteria were set during the classification process; the studied wells have a common geology and trajectory, and they use a very similar bottomhole assembly (BHA) design. The inclination values from the wireline tool are used to illustrate the attainable benefits in terms of wellbore quality and measure wellbore tortuosity. In addition, the wireline inclination data are compared with the actual measurement- while-drilling (MWD) survey to highlight the existence of the micro-dogleg severity (DLS) that cannot be measured by standard surveys. Due to the theoretical differences in the steering mechanism between the various types of RSS, it has been claimed that utilizing one steering mechanism over another can produce a less-tortuous wellbore. These steering mechanisms have previously been classified as either push-the-bit or point-the-bit mechanisms. The relative merits of a push-the-bit steering mechanism vs. a point-the-bit steering mechanism is an over- simplification; neither mechanism can deliver the premium wellbore quality the industry demands from RSS. The present study introduces the continuous proportional steering method (CPSM), and demonstrates how this mechanism can provide superior wellbore quality by reducing wellbore tortuosity. In addition, a superior inclination hold performance is observed in horizontal sections drilled with the CPSM. Curve intervals are more continuous and smoothly drilled through the planned directional changes. The research becomes a useful reference to analyze the performance and efficiency of RSS steering mechanisms across drilling and workover operations. Directional drilling service companies are encouraged and challenged to improve the efficiency and accuracy of RSS mechanisms, improving the hole quality and reducing micro-doglegs.

The history of wellbore trajectory control can be traced back to the days of drilling with rotary assemblies. During that time, experienced directional drillers (DDs) used their knowledge about the response of bottomhole assemblies (BHA) in a specific area or field by means of drilling parameters and assembly configurations changes. This method required intensive field and human experience and still resulted in considerable deviations from the required trajectories. Technologies evolved with the introduction of motor and rotary steerable systems that have additional predicted directional responses, however, considerable human intervention was still required to control the trajectories. As the rotary steerable system (RSS) tools matured, entire sections of the well trajectories were automated with closed-loop trajectory control that required minimum human intervention. However, the curved sections continued to be drilled in manual modes with DDs interventions. A major operator focused on evaluating and validating a novel approach from its major directional drilling service provider using the auto-curve drilling mode to automatically drill the curved sections without human intervention and complete the missing puzzle of the autonomous well construction. The system is based on a minimum curvature method, which updates the target inclination and azimuth in a closed-loop system, similar to the one used in the hold inclination & azimuth method. Expected run rate of penetration (ROP) and planned dogleg severity (DLS) are needed while programming the tool for the RSS calculation update. Once the auto-curve mode is engaged in the RSS tool, updating the target inclination and azimuth will continue along the well to deliver the programmed DLS as per the ROP input. A detailed comparison of the measurements has been performed through three directional drilling curve sections in three wells. Combining the data of the three wells, 5,632-ft were drilled in different sections. The results were promising and showed an average of 70% reduction of human intervention. Furthermore, regarding the well positioning, the new auto-curve automation technology delivered the wells within the required profile target tolerances with minimum tortuosity. The novel autonomous curve drilling technology helped to minimize human error, enhance the accuracy of well positioning, and improve hole quality for drilling and workover operations. The system proved that this autonomous drilling technology is capable of improved well trajectory delivery with minimum intervention, faster well delivery, and reduction in operation costs.

In the present paper, operational accidents, which occur during offshore drilling and production operations are carefully studied. Data were collected from literature for those operations and each accident was classified according to related operations and carefully analyzed. After that, each accident was classified according to the operation unit where it happened, i.e., drilling, completion, production and workover type unit. Classifying the accidents and analyzing the obtained results has shown that more than half of them are related to offshore petroleum production unit operations, followed by those related to drilling rig operations. The remaining observed cases are related to workover exploration and completion units. The evaluation of operational accidents in offshore petroleum drilling and production units could clarify the behavior of operational safety, particularly variations along the years. It was possible to identify the main factors that contribute to the increase of the number of those accidents in offshore units, as well as, the consequences of each accident. Finally, such procedures provided useful information that can assist engineers in making decisions improving operational safety programs for offshore drilling and production unit operations.