A 1999 SPE/IADC paper (52782) identified and documented solutions to a number of drilling problems encountered in Ultra-deepwater drilling. Since that time the industry has pushed the water depth record beyond 10,000' of water and drilling depths below 32,000'. A number of new problems have occurred in the last 8 years that have been caused by mechanical failures (equipment stressed to its limits) or human error. In the Gulf of Mexico recent drilling has encountered problems drilling salt and tar that the industry had not previously experienced. Three operators active in deepwater GOM have collaborated on this paper to document problems under the assumption that understanding what can go wrong is the best way to avoid problems. Introduction In 1999 the water depth drilling record was 7,520'. There were 56 rigs advertised as being capable of drilling in greater than 5,000' of water1. The water depth record is now 10,011' 2 and there are 74 rigs capable of drilling in greater than 5,000' of water3. In the 1990s there were 148 wells drilled in the Gulf of Mexico in greater than 4,000' of water. By the 2000s (mid 2006) there have been 524 wells drilled in greater than 4,000' of water. The authors' companies have drilled 291 of these wells in the Gulf of Mexico since 2000. The number of wells being drilled in deepwater has increased. The water depth, total depth and complexity of those wells drilled in deepwater GOM has also increased. The depth record is now 34,189' MD4.

TX 75083-3836 U.S.A., fax 1.972.952.9435. AbstractA 1999 SPE/IADC paper (52782) identified and documented solutions to a number of drilling problems encountered in Ultra-deepwater drilling. Since that time the industry has pushed the water depth record beyond 10,000' of water and drilling depths below 32,000'. A number of new problems have occurred in the last 8 years that have been caused by mechanical failures (equipment stressed to its limits) or human error. In the Gulf of Mexico recent drilling has encountered problems drilling salt and tar that the industry had not previously experienced. Three operators active in deepwater GOM have collaborated on this paper to document problems under the assumption that understanding what can go wrong is the best way to avoid problems.

Various indirect measuring techniques are presently employed for estimating formation strength, which in turn is correlated to drillability and polycrystalline diamond compact (PDC) bit selection. Formation mechanical properties derived from conventional open-hole logs in combination with a rigorous assessment of formation shear wave velocities can be used successfully to determine drillability as it pertains to bit selection. Formation drillability is best determined from unconfined compressive strength and the angle of internal friction assessment. Rock strength is found to correlate well with the overall measures of bit effectiveness. Further, the angle of internal friction, which is a subsidiary rock strength parameter, correlates with PDC bit wear rates. Compressive strength and drillability have been linked in the laboratory and observed in the field since the early 1960's. Compressive strengths, however, need to be qualified as a function of confinement stress. The concept that compressive strength increases with confinement stress is well-understood and can be easily explained with Mohr's failure criteria. With the Mohr's failure technique, it is important to understand that inherent rock strength properties (cohesion and angle of internal friction) must be known before compressive strengths can be estimated. This paper also presents case histories from Gulf of Mexico wells that illustrate how unconfined compressive strength and angle of internal friction can be employed to indicate drillability as it pertains to optimized bit selection. Introduction Aggressiveness and wear resistance are two fundamental properties that must be considered when selecting a bit for a specific application. For simplicities sake, these two bit properties, while not totally independent, may be considered separately. The aggressiveness of the bit is determined by the depth of cut it is designed to take. In roller cone bits, aggressiveness is determined by projection, pitch of the teeth, and cone offset. In PDC bits, aggressiveness is determined by the exposure of the cutters and the cutter angle (backrake). Wear resistance, on the other hand, is determined by the density of the cutters, especially those on and near the gauge. In roller cone bits, increasing wear resistance is accomplished by adding more gauge cutters; more durable shapes of cutters; applying diamond to the cutters that contact gauge; and modifying carbide grade (at the expense of making cutters more brittle) or increasing the number of carbide inserts on the shirttail. P. 569

SPE Members Abstract This paper describes a drilling data acquisition and telemetry system that is currently in use in the U.S. Gulf Coast. The system provides for the real time monitoring of up to 20 drilling rigs. Drilling data are acquired at the rig site and transmitted into a central office onshore over microwave or satellite telemetry links. The data acquisition units are advanced computer mud logging units that are capable of recording over 200 surface parameters relating to the drilling system. The data parameters are displayed in the central data facility in real time on graphic displays. The data parameters are subsequently analyzed in the office and used for providing safer rig operations through backup providing safer rig operations through backup surveillance, improving rig management practices and for performing interpretive data processing using performing interpretive data processing using drilling engineering models. Drilling costs have been reduced by using this system. For example, the monitoring of connection times has led to a time savings of up to 1-1/2 days/month/rig. The paper will describe the processing and handling of the data in the central office facility. The cost savings thus far quantified will be explained. Introduction In the late 70's and early 1980's, Gulf of Mexico drilling costs were increasing rapidly with corresponding decreases in efficiency. Tenneco, a major Gulf of Mexico operator, made the decision to develop an extensive drilling data base to improve drilling efficiency and thereby improve- the cost effectiveness of their yearly drilling budget. The real time data system was the principle tool selected to meet this goal. Tenneco has over 124 producing platforms in federal waters in the Gulf of Mexico and operates 6-12 drilling rigs year-round. The data supplied by the real time system aids in providing a safe and efficient drilling operation in the Gulf of Mexico. The system has proven to be cost effective on a per rig basis. Data obtained from the system have been used for real time applications, office support functions, and performance evaluation. The system is capable of handling up to 20 rigs and was developed by NL Baroid Logging Systems (BLS). The initial start up of the computer system was in September 1983. APPROACH The ability to gather data from a large number of wells across the Gulf of Mexico has generated a ussable, multipurpose data base. Detailed analysis and comparisons can be performed in the areas of rig time utilization, rig performance, drilling parameters, tripping, cementing, circulation and related parameters, tripping, cementing, circulation and related rig activities. In addition, the data base provides vast information for detailed drilling studies and the verification of the models resulting from these studies. Acquiring drilling data at the Well site can be done through many different methods.' For this real time system, it was decided to utilize available computerized manned mud lodging units, thereby negating the need to develop a new drilling data gathering system. Microwave communications are typically used to transmit data from the rig to a Central Site Data Center (CSDC) for processing, storage, and display. The CSDC is located in Tenneco's Offshore Division office in Lafayette, Louisiana. The data are displayed on printouts, plots, CRT, displays and graphics for use by plots, CRT, displays and graphics for use by drilling engineers and geologists. An example of how data is transferred is shown in Figure 1. Data is initially obtained at the rig through various drilling sensors. The sensor reading is transmitted via an electrical signal to the computerized mud logging unit. Currently, eight mud logging vendors have adapted their software to interface with the real time system. The current system transmits up to 352 parameters every 15 seconds on a 24 hour/day basis. Some of the commonly used drilling parameters are shown in Figure 2. parameters are shown in Figure 2. Real time data can be archived on a foot by foot basis or on selected time intervals, depending on operation. Whereas in the past, drilling data recorded with the conventional mud log was normally archived on a five foot basis. The advantage of this one foot spacing is that it allows more detailed analysis of drilling trends and situations, i.e. torque, ROP, etc. P. 589

Compliance with governmental regulations is a major concern for all offshore operators and contractors who drill in Outer Continental Shelf (OCS) waters. Drilling operations in these waters come under the jurisdiction of the Mineral Management Service (MMS). Failure to comply with these regulations can result in being issued a written notice called an incident of non-compliance (INC), rig opera-tions shut down, or depending on the severity of the infraction, fines and imprisonment. This paper will review MMS Order 250- -Subpart D (Drilling Operations), which replaced OCS Order 2 in 1988. The intent is not to debate the merits of the new Orders, but to examine their present and future impact on operating practices, from both safety and economic perspectives.