Today important parameters to enable a reduction of lost and hidden lost time during drilling, like hook loads for pulling and slacking off the drill string, and torque for drill string rotation, are still taken manually. Analysing torque trends during drilling and reaming is hardly done.A key to reduce lost and hidden lost time by analysing drilling data is to automatically recognize ongoing operations in real time from this data. That allows the automatic identification and picking of pulling-up; slacking-off and rotating hook loads, as well as torque values without spending extra time or work force. Relevant parameters can be sampled and analysed automatically in real time from the rig sensor data stream without interfering drilling operations. This automated process allows monitoring changing torque and drag trends for each stand of drill string moved during drilling, tripping, or reaming operations. To monitor trends in the torque and drag development in real time, parameters may be combined with simulated hook load and torque curves in a graphical way. Simulated values are imported from engineering applications. This allows the user to react immediately, not only after hand taken values are manually entered into a graph. The possibility to broadcast all the data to computers worldwide enables a great level of cooperation. Instant measures against increasing torque and drag can be taken before reaching critical ranges on a stand per stand basis. Also excessive reaming and washing can be avoided as low torque and drag may be an indication for a good hole quality. This can save wellbore treatment time. The paper presents the development of the system, its validation against live well data from recent 20,000ft wells in the Vienna basin and the planned application of the system on an extended reach field development project offshore New Zealand.

Sour gas and high-strength steel are generally accepted to be incompatible. However when drilling beyond 20000ft S135 and higher steel grades become necessary to support their own weight, and due to the elevated down hole pressures in the range of 15–20ksi, even minimal concentrations of H2S result in partial pressures that are considered hostile for these steel grades. The paper presents initial results from a joint industry project exposing S-grade drill pipe samples to various H2S concentrations in temperature ranges from 70–170°C and exposure times of 1–3 hours, representing typical conditions when circulating a gas kick to surface. Test conditions have been designed to closely recreate actual down hole conditions, with actual potassium carbonate drilling fluids saturated with hydrogen sulphide and an additional free gas phase. After exposure to the sour environment, the samples have then been taken to fatigue testing to evaluate actual damage against undamaged base-line fatigue results. Introduction Sour drilling environments where H2S gas is present and sour-gas kicks are possible can lead to Sulfide Stress Cracking (SSC) failures in steel drill pipe. In practice, a combination of stress, an environment containing H2S and a susceptible material are required for SSC to occur. SSC occurs as a result of atomic hydrogen entering the steel. Once inside the metal, the atomic hydrogen diffuses to initiation sites where in can cause localized increases in stress or a reduction in the strength of the material lattice. It is generally agreed that brittle H2S induced cracking is closely related to hydrogen embrittlement as a result of the ingress of hydrogen into the stressed material. Hydrogen is a problem in most steels because it is highly mobile in atomic form and can both diffuse through and be transported by the movements of dislocations. Hydrogen embrittlement can result in either a loss of ductility or a cracking phenomenon. Conditions that promote SSC in drill pipe include high tensile stress, high concentrations of H2S, low pH, high pressure, high chloride content, lower temperatures and high material hardness (higher strength steels generally have higher hardness properties). Material selection for drill pipe in sour applications is significantly more complex than material selection for production casing and tubing in similar well applications due toa more close controlled and known environment by the time casing and especially tubing strings are run, andthe defined requirement for these strings to survive long-term exposure to corrosive atmosphere whereas drill strings will only be exposed for a short time during a loss of hydrostatic equilibrium in the well. Production casing and tubing designers determine if the well parameters create a sour service environment as defined by NACE MR0175. Production casing and tubing materials resistant to SSC are required if the system contains water as a liquid, the H2S partial pressure exceeds 0.05 psi and the system pressure is greater than or equal to 65 psi or 265 psi depending on the gas:oil ratio of the system.

Monitoring the borehole condition during the ongoing drilling process is essential for a successful and safe drilling operation. The drilling industry has developed monitoring systems, which offer the possibility to analyze torque and drag effects in real time and typically calculate a borehole pseudo friction factor. The paper presents a new approach of analyzing recorded drilling data by directly using hook load measurements. The target of the analysis is to minimize the time spent on ream and wash operations. Furthermore the proposed method can be used as an indicator of developing borehole problems at an early stage before they become critical to the operation. The method is based on the comparison of the hook load during pick-up and slack-off movement of the drill string while reaming one stand of drill pipe prior to making a connection. A characteristic signature is generated, which is then interpreted automatically. The result shows whether the well bore conditions allow to resume operations or indicate continued reaming, thus optimizing the number of reaming trips and subsequently reducing the total amount of non-productive time. Based on the comparison of ream and wash sequences of subsequent drill pipe stands, it is possible to generate an automatic well bore condition log, which shows well bore sections with abnormal behavior. The paper shows that it is possible to identify non-problematic well bore conditions and to avoid unnecessary ream and wash operations. A software package offers the possibility to post analyze recorded data as well as the evaluation of real-time data. A case study shows the technical and economic potential of this new approach. Introduction During the drilling process it is necessary to obtain immediate information on current downhole conditions in order to take remedial actions in case of an existing or developing drilling problem. Therefore online techniques have been developed, which continuously monitor drilling conditions and evaluate drilling performance. Considering the trend to record more and more different data volumes at ever-higher frequencies, it is necessary to find methods to reduce and condense the amount of data presented, without loss of important information. Furthermore it must be the target to avoid analysis primarily based on manual (i.e. visual) interpretation of a multitude of log type curves. Previous investigations1 tried to calculate a friction factor log with surface measured data in real-time, which was used for identifying hole cleaning problems, stuck pipe, differential sticking, formation change and mud lubrication problems. The authors defined different type curves of hookload patterns comparing tripping out hookload data against these different type curves. At a second stage a so-called pseudo friction factor analysis was performed, if needed. The current paper is an evolution of this concept, automating the analysis by utilizing rule-based algorithms in combination with statistical analysis in a hybrid system. The preprocessing of the recorded data, with the recognition of different operations patterns with the intention to reduce the amount of data to be stored, is used as a means to condense the amount of information presented to the user to a manageable volume2. The objective of the proposed analysis is to reduce ream and wash time during drilling as well as increase drilling performance by timely detection of onsetting downhole problems. The ream/wash-induced non-productive time, which due to its short duration is normally not listed explicitly in the daily drilling operations report, is typically lumped into the drilling time, such as connection time, and therefore represents hidden non-productive time. The basic concept of this work is to recognize such operations automatically and to obtain information about changes of the drilling environment focusing on the time-based ream and wash sequences after a stand has been drilled down. Typically multiple up and downward movements of the drill string over the entire length of the stand are performed. The hookload patterns during these sequences represent a kind of "borehole log", and they have been subject to further investigations.

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One essential element of real-time drilling monitoring is wellbore hydraulics reflected by fluid flow and pressure response. Issues related to pipe wash-outs, cuttings accumulations and well control create a significant source of drilling related problems and consequent lost time. In addition to lost time incidents, the optimum processes to clean and condition the hole in relation to hydraulics are a significant potential in avoiding hidden lost time. This paper outlines a concept and several case studies to monitor drilling hydraulics by analysing fluid flow in relation to pump pressure and other relevant sensor channels. Objective of this work is to early recognize the on-set of hydraulics related problems to take preventive action. The concept is based on recognizing variations in expected behaviour of rig sensor responses using hybrid algorithms, which link analytic, statistic and knowledge based concepts. With a large number of data at a high degree of operational detail, generated using automated operations recognition, it is possible to identify patterns, which allow the early detection of a number of problems, such as pipe washouts, circulation losses, as well as stuck pipe. The analysis of routine drilling operations, like pump start-up, allow the optimization of the drilling process to avoid hidden lost time. The interpretation of the related patterns allows optimizing pump start-up procedures and shows trends in changing wellbore behaviour over time. The concept is implemented by a hydraulics monitoring screen fed by the results of the automated analysis, which outlines the ideal operating window to enable the drilling personnel to act on the information generated.