The anticipation and remediation of operational problems while drilling an oilwell is the main goal of real time measurements of drilling parameters, such as bottomhole pressure, flow rate, pump pressure, torque, drag, among others. The petroleum industry has spent a great amount of financial resources to ensure the quality and availability of these data, but the knowledge for a correct analysis and interpretation of them is still far from being spread among the rigsite teams and drilling engineers. Nowadays, the interpretation of real time drilling data to identify possible operational problems is done by a drilling analysis specialist. However, this can be a very subjective job since it depends on the specialist experience. These analists also take their decisions based on intuition and qualitative rather than quantitative criteria. Petrobras has developed a computational tool (called PWDa) to interpret real time drilling data, predicting and analyzing drilling operational parameters (such as pump pressure, bottomhole pressure, torque and drag). The software detects abnormal behaviors (such as an unexpected increasing trend on bottomhole pressure) and establishes quantitative criteria in order to identify a possible cause, suggesting corrective and/or preventive actions. The main goal of the software is the establishment of an automated methodology to interpret operational parameters in real time helping the drilling engineers to take right and fast decisions. The software is being currently implemented at Petrobras Real Time Operations (RTO) rooms and is providing good results. Over 70 wells have already been monitored with PWDa and several operational problems (such as washout, mud losses, bit wear, downhole motor fail, deficient hole cleaning, pore pressure increments, etc) were successfully identified, allowing the operators to take fast decisions and avoiding riskier situations. The wells monitored include deep water exploratory wells (mostly), directional development wells and extended reach wells. This work aims to highlight the benefits generated by the implementation of the technology. The interaction with the drilling team, including operator and service company members will be discussed. Introduction The analyzis of PWD (Pressure While Drilling) data and other operational parameters (such as rate of penetration, standpipe pressure, flow rate, torque, drag, etc) is an important tool to identify and prevent several operational problems (Aragao et al). The real time interpretation of these data may be very useful to reduce non productive time, risks and operational costs. According to Teixeira et al, most of events and problems have direct or indirect impact on bottomhole pressure and standpipe pressure. Some of them may also affect torque and drag. Problems like poor hole cleaning, annular obstructions, wellbore collapse, kicks, washouts and mud losses will affect the amount of solids in the annular space and/or friction losses and, therefor, will directly affect standpipe and bottomhole pressure (Aragao, et al, 2005). Thus, the analysis of pressure data is a key element to identify and prevent operational problems. Additionaly, when other parameters are simultaneously analyzed (modlogging measurements, for instance), the interpretation becomes much richer.

TX 75083-3836 U.S.A., fax 1.972.952.9435. AbstractFast and non-progressive drilling fluid gelation is desired to prevent drilled solids sedimentation during pumps-off, while avoiding excessive pressure peaks when circulation is resumed. Gelation tendencies are normally higher at low temperatures typical of deepwater risers. Excessive pressure peaks can cause detrimental effects when fracture pressure is reached.Besides gelation issues, excessive pressures and/or difficulties to resume circulation have been observed during drilling operations in water depths greater than 1.800 m. The problem happened especially with the fluid volume filling the control lines, at the time of circulation restart. Two field cases of fluid freezing in choke and kill lines have been reported which led to riser and BOP removal to unplug the lines, with significant non productive time and high costs.The paper shows the results of an experimental study carried out to evaluate the rheological behavior and gelation properties of non aqueous drilling muds under low temperatures (bellow 4 o C) and high pressures (up to 5.000 psi). The study aimed to quantify pressure effects on freezing temperatures and to develop representative methodologies for the evaluation of thyxotropic properties of such fluids. Experiments included steady state and transient shear and oscillatory tests at cone-plate geometries. The final goals are to design additives and drilling fluid formulations with flow point lower than 0 o C at pressures higher than 2.500 psi and taylor made gelation profiles. Additionally modeling work was carried on to represent the time dependent behavior of relevant rheological properties at different temperatures and pressures. Such models were used to predict pressure peaks and compare them with real PWD data from ultra deepwater wells.

This article details the field implementation experience of an in house developed system for drilling problems detection and identification. Starting from real time drilling data (including MWD, PWD and mud logging sources), the system was designed to investigate reasons for deviations in important measured variables (such as downhole and pumping pressures, temperatures, torque and drag, etc.) during drilling operations. Based on a hybrid approach, including multi phase hydraulics and torque & drag modeling, case history matching and specialists knowledge, the system should identify undesirable events, such as influxes, poor solids transport, bit balling, bit wear, drillpipe washouts, hole instabilities among several others.Field implementation issues includes offshore installations and remote operations from onshore decision support rooms, necessity of team working, requirements for conventional and MPD operations, software calibration and validation challenges and continuous knowledge updating. Examples highlight the benefits on investing in data interpretation and drilling automation technologies for deepwater exploratory scenarios.

TX 75083-3836 U.S.A., fax 1.972.952.9435. AbstractFast and non-progressive drilling fluid gelation is desired to prevent drilled solids sedimentation during pumps-off, while avoiding excessive pressure peaks when circulation is resumed. Gelation tendencies are normally higher at low temperatures typical of deepwater risers. Excessive pressure peaks can cause detrimental effects when fracture pressure is reached.Besides gelation issues, excessive pressures and/or difficulties to resume circulation have been observed during drilling operations in water depths greater than 1.800 m. The problem happened especially with the fluid volume filling the control lines, at the time of circulation restart. Two field cases of fluid freezing in choke and kill lines have been reported which led to riser and BOP removal to unplug the lines, with significant non productive time and high costs.The paper shows the results of an experimental study carried out to evaluate the rheological behavior and gelation properties of non aqueous drilling muds under low temperatures (bellow 4 o C) and high pressures (up to 5.000 psi). The study aimed to quantify pressure effects on freezing temperatures and to develop representative methodologies for the evaluation of thyxotropic properties of such fluids. Experiments included steady state and transient shear and oscillatory tests at cone-plate geometries. The final goals are to design additives and drilling fluid formulations with flow point lower than 0 o C at pressures higher than 2.500 psi and taylor made gelation profiles. Additionally modeling work was carried on to represent the time dependent behavior of relevant rheological properties at different temperatures and pressures. Such models were used to predict pressure peaks and compare them with real PWD data from ultra deepwater wells.

This article summarizes efforts conducted by PETROBRAS and partners aiming offshore oilwell drilling automation. The first step includes the implementation of a drilling problem detection software which operates with online real-time data analysis. The second step includes the concept of an integrated model to represent the process of drilling and the third an experimental pilot scale facility constructed to test control algorithms for MPD and influx control operations.