Liners hangers are used in deep drilling operations to eliminate the need to run full strings of casing. Unlike regular casings that are installed back to surface; liners will be terminated downhole at a hang-off point in the last casing. Deploying liner hangers can be very difficult, depending on the wellbore conditions. In many scenarios, the bottomhole assembly (BHA) must be rotated and/or reciprocated in order to set the BHA at the target depth, and conventional liner hanger systems often do not permit tool rotation due to the complex design. Liner-hanger failures ultimately can be the cause for losing the wellbore or a section of the wellbore, which in turn, will result in additional well construction costs to sidetrack and drill another section through the production zone. This paper will discuss the use of an expandable liner hanger that has a less complicated design that withstands aggressive reaming as well as drilling to depth. This expandable system has no external moving parts such as slips, hydraulic-setting cylinders or separate liner-top packers, which are used in conventional liners. These attributes help mitigate the risks associated with the deployment exercise and the complexity of the completion. PDVSA embraced this technology to help them optimize operations in their deep wells in which extreme environments, often close to 300°F, with deviations greater than 60 degrees and setting depths of more that 12,000 feet are encountered. The benefits that have been gain by adopting this technology are:Optimized capital expenditureOptimized rig-time efficiency (reduced NPT)Avoidance of costly redundant conditioning trips, hanger damage, and premature settingElimination of external moving parts on hanger assembly (reduced complexity)Reduced rig timeImproved reliability and fluid flowNo slip damage to supporting casing Case histories that compare the traditional and expandable liner hanger systems and verify the advantages stated above are presented. Introduction The two case history wells discussed in this paper are located in the state of Barinas and Apure in Southern Venezuela (Figure 1). Using expandable liner hangers in Barinas and Apure have provided two very important functions in the well construction process. The first function was to support the weight of the liner, and the second was to provide a positive seal on setting that would isolate pressure differentials between the wellbore section above the liner hanger and the wellbore section below the liner hanger. A common problem in the industry concerns the fact that failure of conventional hangers normally occurs during the deployment of the liner or during the setting process, which can be due to a variety of reasons:Cement integrity at the liner top (Agnew, et al, 1084)Premature setting of the liner hangerInability to reach target depthProblems with conventional tools (darts, plugs, setting tools, etc.).

Good perforating design is essential in maximizing the value that can be pulled from the reservoir. Poorly-planned and/or executed perforating strategies in high-pressure, deep-water wells can easily increase operational costs and reduce production and revenue streams. With the increased demand for oil and gas over the last decade, operators have been forced to explore deeper to find the most prolific reservoirs to meet this growing need. In the U.S. Gulf of Mexico, these deep-water opportunities have required constant improvements to equipment and services to increase their technical capabilities for performing in more critical environments while minimizing non-productive time (NPT). Higher shot densities, propellants, larger perforating guns, electronic firing heads, shrouded assemblies, and dynamic shock modeling have been used to meet these new challenges. A major problem with these deep wells is the increased cost it takes to develop them. The use of more powerful perforating systems to increase flow area is required to maximize well productivity and recoup this cost. With the use of such systems comes the additional explosive load and the difficulty in predicting dynamic wellbore behaviors that could cause tubulars to burst, collapse, bend, buckle, and shear, as well as tubing to move excessively, packer seals to fail, and packers to unset as perforating guns are detonated. Understanding and mitigation of dynamic events at gun detonation, in addition to solid loading imparted to the tubulars, packers, and other completion hardware in the perforating assembly, were needed if the industry was to continue exploring new frontiers with complex challenges. A high-confidence level was needed to use these larger gun assemblies to go forward with these well completions without incurring NPT. This paper discusses a successful execution of a high-pressure, deep-water shoot-and-pull job with a custom-designed bottomhole assembly to address casing integrity challenges and the dynamic shock-modeling software program that evaluates the mechanical integrity of all well components.

Oilwell casing perforating has been used in the industry since 1932 and was pioneered by the Lane-Wells Company who introduced the bullet-gun perforating technique. Shortly after the introduction of the bullet gun, explosive jet perforators were introduced, which provided a different and more aggressive way to perforate casing.With the increased demand for oil and gas over the past decades, operators have been forced to explore deeper, hotter reservoirs to find the most prolific reservoirs. These deepwater opportunities have required constant changes to equipment and services to increase their technical capabilities for performing in more critical environments. Perforating with higher-shot densities, propellants, and larger perforating guns has been ongoing to meet these new challenges.A major problem with these increases, however, is the difficulty in predicting dynamic wellbore behaviors that cause tubulars to collapse and bend and packers to unset as perforating guns were detonated. Research to understand the pressure behavior during the perforation event, in addition to the solid loading that is imparted to the tubulars, packers, and other completion hardware in the perforating assembly, was needed to enable the industry to go forward with a high level of confidence that wells could be completed safely and cost effectively.This paper discusses a shock-wave computer modeling program that evaluates the mechanical risk factors of well components to ensure that the health, safety, environment, and service quality needs in a design are addressed. A timemarching, finite-differences technique is applied as the numerical method for both fluids and solids. The software is installed on a personal computer and typically executes the models within several minutes to several hours, depending on the complexity of the job design.The physics-based model has been validated (Schatz et al. 1999;Schatz et al. 2004) with special high-speed recorders that sense pressure, temperature, and acceleration at a sampling frequency of 115,000 samples per second.This paper provides data from offshore oil and gas wells in the Gulf of Mexico to demonstrate the success of the design.

No abstract

Oilwell casing perforation has been used in the industry since 1932 and was pioneered by the Lane-Wells Company who introduced the bullet-gun perforating technique. Shortly after the introduction of the bullet gun, explosive jet perforators were introduced, which provided a different and more aggressive way to perforate casing.With the increased demand for oil and gas over the past decades, operators have been forced to explore deeper, hotter reservoirs to find the most prolific reservoirs. These deepwater opportunities have required constant changes to equipment and services to increase their technical capabilities for performing in more critical environments. Perforating with higher-shot densities, propellants, and larger perforating guns has been ongoing to meet these new challenges.A major problem with these increases, however, is the difficulty in predicting dynamic wellbore behaviors that cause tubulars to collapse and bend and packers to unset as perforating guns were detonated. Research to understand the pressure behavior during the perforation event, in addition to the solid loading that is imparted to the tubulars, packers, and other completion hardware in the perforating assembly, was needed to enable the industry to go forward with a high level of confidence that wells could be completed safely and cost effectively.This paper discusses a shock-wave computer modeling program that evaluates the mechanical risk factors of well components to ensure that the health, safety, environment, and service quality needs in a design are addressed. A timemarching, finite-differences technique is applied as the numerical method for both fluids and solids. The software is installed on a personal computer and typically executes the models within several minutes to several hours, depending on the complexity of the job design.The physics-based model has been validated (Schatz et al. 1999 andSchatz et al. 2004) with special high-speed recorders that sense pressure, temperature, and acceleration at a sampling frequency of 115,000 samples per second.This paper provides data from offshore oil and gas wells in the Gulf of Mexico to demonstrate the success of the design.