Current methodologies for drill planning, widely implemented by Oil Companiesto optimize the definition of technical and economic options for the drillingprocess, are based on a scrupulous analysis of the production requirements, thetechnical risks, and the geological uncertainties. Planning and designingdrilling projects begin by considering the problems observed in correlationwells drilled in the same field, in order to obtain a successful mechanicalmodel. Once the drilling process begins, an evaluation of the continuing operationsallows drilling engineers to control and adjust the differences that may arisebetween the drilling plan and the actual conditions observed while drilling. These identified variations are related to uncertainties in the criticaloperational parameters, such as pore pressure and fracture pressure gradients, salt intrusions, and changes in the planned lithology column, such as, shaledomes, and gas shows. Dealing with these variations is imperative, as they candetermine either the success or the failure of the well. This Paper proposes a Real-Time Drilling Engineering Methodology that allowsoperations staff to drill ahead in depth and time by anticipating geological, mechanical and operational conditions, thus allowing preemptive actions. ThisMethodology allows forecasting the adequate drilling parameters by visualizingthe current conditions of the well. These include the analysis of theinteraction between the drill string and the fluid with the formation, thenormalization of mud densities in the areas of interest, and the analysis ofgeopressures from logging-while-drilling data. Other parameters that need to beconsidered might include the variation of casing and hydraulics designs, andthe optimization of the well path from Real-Time Trajectory and Log Data. This Real-Time analysis leads to immediate engineering recommendations that caneliminate and avoid ongoing and potentially undesirable situations whiledrilling, such as stuck pipes, gasifications, and runoffs, thereby allowing apreemptive response to the variations that may occur between the proposeddrilling plan and the actual drilling conditions. By applying this Methodologyin several oilfields in Southern Mexico, an observed 20% increase of thetechnical efficiency of the drilling process has been reported, resulting inover 80% of the wells operating under normal conditions, with a reduction inthe average cost of the well for the operator.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIn the PEMEX Southern Drilling and Producing Region, which includes all land wells drilled in the southeastern states of Mexico, directional drilling has gradually increased to 75% of wells drilled. Producing zones in the region are also deep with difficult targets under high pressure and temperature. These factors have led PEMEX to seek out new technology in an effort to optimize drilling and producing operations.One of the special projects defined for the year 2001 was to evaluate the application of running a high-accuracy gyroscopic directional survey instrument in tandem with PEMEX logging systems. In the process, the Southern Region engineering group and the PEMEX wireline logging division worked with a local survey company to build a special housing to run the gyro probe on top of several different logging instruments. This paper describes the development of the tandem gyrologging combination tool and tests in three wells. System performance is analyzed and comparisons are made between gyro survey results and other survey instrumentation. Conclusions indicate that the success of running two services in one run in the well saves substantial rigtime and eliminates the costs of additional wireline runs. Furthermore, the application of high-accuracy survey information may prove valuable in more accurate wellbore placement and reservoir mapping-leading to enhanced production. In the future, the combination run may also have value in detecting the orientation of imaging logs in both cased and open hole to determine fracture orientation and formation dip angle.

This paper describes the events leading to the collapse of a 9 7/8" liner over a 7 5/8" casing while drilling a depleted fractured reservoir (high inclination, 150°C BHST) using the concentric injection technique and Managed Pressure Drilling (MPD) in well "A" in the South of Mexico. It also illustrates the investigation process conducted aimed at the identification of the potential failure scenarios. Finally, a new casing design approach for wells under these challenging conditions based on limit state design and deterministic load estimate has been developed and implemented as a result.