Testing and gathering data from a well to evaluate the potential of a new field is a common practice in the oil and gas industry. However, performing this task in a subsea environment to test a well in ultra deep water presents significantly greater challenges to the operator and service providers. Since testing in the depths required for the subject well had not previously been attempted, there were concerns of problems that might occur in maintaining response times and control of the test equipment. This paper will present the innovative solution that was devised to perform the evaluation testing in the deepest offshore producing well in the world (1,853 meters or 6,079 feet) from a drill ship with conventional subsea equipment. The equipment, the well, location conditions, and procedures that were used to safely and efficiently perform the evaluation testing will be discussed.To date, this has been the deepest well in which this function has been successfully performed. From the well testing data gathered, the Petrobras Reservoir Engineering and Geology Departments were able to determine production potentials, which indicated that this was the most important discovery of the last few years, as well as to obtain information that would be invaluable for field development. It is anticipated that the field will have an estimated oil production of 180,000 BOPD and 4.8 mm m 3 of gas by the year 2,000.

Testing and gathering data from a well to evaluate the potential of a new field is a common practice in the oil and gas industry. However, performing this task in a subsea environment to test a well in ultra deep water presents significantly greater challenges to the operator and service providers. Since testing in the depths required for the subject well had not previously been attempted, there were concerns of problems that might occur in maintaining response times and control of the test equipment. This paper will present the innovative solution that was devised to perform the evaluation testing in the deepest offshore producing well in the world (1,853 meters or 6,079 feet) from a drill ship with conventional subsea equipment. The equipment, the well, location conditions, and procedures that were used to safely and efficiently perform the evaluation testing will be discussed. To date, this has been the deepest well in which this function has been successfully performed. From the well testing data gathered, the Petrobras Reservoir Engineering and Geology Departments were able to determine production potentials, which indicated that this was the most important discovery of the last few years, as well as to obtain information that would be invaluable for field development. It is anticipated that the field will have an estimated oil production of 180,000 BOPD and 4.8 mm m3 of gas by the year 2,000.

This paper was also presented as SPE 68762 at the 2001 SPE Asia Pacific Oil and Gas Conference and Exhibition, 17–19 April, Jakarta, Indonesia. Abstract This paper will describe the first coiled-tubing-conveyed perforating (CTCP) jobs performed offshore in a horizontal well in the Campos Basin, Rio de Janeiro, Brazil. The operation was needed to obtain the objectives sought after for this well and also to provide a "learning curve" for a major job that was to be run subsequent to this job using the same method. The second job was to be in a water depth of 968 ft., and more than 1,000 ft. of guns would be run. Both jobs will be discussed in this paper along with the advantages gained on the second job from the first experience. The first procedure required perforating of a 262-ft. interval in a 92-degree horizontal well using 2 in., 6 SPF super deep penetration scalloped guns that would be coiled-tubing deployed through 3–1/2 in. production tubing. The operation was to be performed from a semi-submersible platform, and the running and retrieving of the perforating guns would have to be accomplished without killing the well so that damaging completion fluids would not come into contact with the reservoir. Requirements for the job were that a safe method be used and that equipment and operational costs be kept at minimum so that a greater return on investment could be realized. Operational conditions included the following:Perforation was ato be conducted with the well in an underbalanced condition so that no formation damage would be sustained.The operation had to be run from a semi-submersible 5that was set in a water depth of 430 ft. (2nd job performed in a water depth of 968 ft.)The gun assembly would have to pass through a 2.81-in. minimum ID. He two jobs were completed under live well conditions, and both were successful. The estimated cost saving from elimination of 3 days of rig time for the second job was approximately $360,000. Even more significant for this technology, there are no documented jobs in which this perforation length has been attempted anywhere in the world from a semi-submersible or where the water-depth distance was used as a lubricator for the guns. Introduction Coiled tubing has been used for several years to deploy perforating guns, and this technology has enabled many operators to use the latest techniques to complete high-angle wells with optimum completion designs. Until recently, however, this perforating method was not used in Brazil because of the complexity and risks involved, particularly on offshore platforms (semi-submersible rigs and/or drill ships) where daily costs are extremely high. For twenty years, Petrobras has been developing state-of-the-art technology for deepwater environments in order to determine best practices to realize the most efficient production. From the time of its first oil production in 1977, the Campos Basin, located off the northern part of the state of Rio de Janeiro has been proving its potential as a major oil-producing province. Already responsible for three-quarters of the country's production, Campos is by far the main production area in Brazil. During those twenty years, 66 fields have been discovered, and exploration and drilling operations are ongoing. (See Fig. 1) This paper will cover two CTCP jobs that were performed in the Moreia and Albacora Fields. The Moreia Field, in which the first job was performed, reaches water depths of 430 ft, and the Albacora Field, where the second job was performed (because of the success of the Moreia job), reaches water depths of ± 1000 ft. The jobs were performed from a semi-submersible platform. (See Fig. 2)

Stimulation combined with perforating during a drill stem testing (DST) operation offers a unique operational technique that shows promise of resolving many inherent formation damage problems that can occur when perforation is conducted during completion activities. This paper will discuss a case history in which a unique perforation-stimulation operation was attempted for the first time in Brazil. The method was suggested to a major operator who wished to test a damaged formation of an exploratory gas well in the Mato Rico Field in Parana Basin, Brazil. The primary requirement of the operation was to obtain the main reservoir parameters (pressure, permeability, skin and extension) of a sand formation in which an earlier openhole drill stem test had already identified severe near-wellbore damage. Since the procedure would not involve the main target of the well, extreme cost efficiency was required. With the method suggested, a well with an acid fluid column is pressurized with nitrogen to above fracturing pressure of the formation before the gun is fired. Gas is then injected with acid to create short fractures extending from the perforation tunnels. The presence of gas lowers the amount of liquid contact with the formation plus the additives in the acid reduced surface tension. This action facilitates the well's coming into production after perforation and results in a reduction of formation damage. The perforating/stimulation method creates highly conductive short fractures that outweigh any restriction that might be caused by the perforating debris. The extreme energy at the moment of perforating along with the rapid expansion of the high-pressure nitrogen gas create high erosion velocities that remove perforation debris from around the wellbore and extend the perforations several feet into the formation. Following the initial perforation, additional pumping of nitrogen extends the created fractures even further into the formation. The debris and the crushed zone that exists when the guns detonate will be pushed away from the wellbore during the pumping stage. This will greatly diminish any adverse effects that overbalanced perforating may cause in productivity. After careful review of alternative methods, this procedure was chosen. It provided excellent testing results and was successful in removing most of the previously identified skin damage. This was verified by the subsequent testing, which showed that the skin damage had been reduced to 14 from its original 89. This reduction allowed the same quantity of gas to be produced at a lower drawdown. The positive effects from using the combined technologies include:Savings in rig time.Time and cost of additional stimulation jobs to flow the well had traditional procedures been used.Better understanding of the formation response to stimulation treatments and fluids.A significant increase in the gas production from an originally estimated 10,000 m3/D to 380,000 m3/D. Introduction This paper concerns an exploratory well, the Matorico, which is operated by Petrobras in the Parana Basin in Brazil. Earlier testing had already identified that there was heavy skin damage. Fig. 1 is a photo of the well and a map showing the location of the well. The goal of the operator was to move enough volume of fluid from the reservoir to obtain the most complete evaluation possible and perform the operations needed with one trip into the well.

Coiled tubing has been used to deploy perforating guns for several years, and use of this technology has enabled many operators to complete high-angle wells with optimum completion designs. Until recently, however, this perforating method was not used in Brazil because of the complexity and risks involved, particularly on offshore platforms (semisubmersible rigs and/or drill ships) where daily costs are extremely high. This paper will describe the first experience of coiledtubing-conveyed perforating (CTCP) performed offshore in a horizontal well in this South American country.The first CTCP job was to be performed not only to obtain the well objectives needed for the well but also to be used as a "learning curve" for a major job that was to be run subsequent to this job using the same method. The second job was to be in a water depth of 968 ft. and more than 1,000 ft. of guns would be run. Both jobs will be discussed, along with the advantages gained on the second job from the first experience.The first procedure required perforating of a 262-ft. interval in a 92-degree horizontal well using 2 in., 6 SPF super deep penetration scalloped guns that would be coiled-tubing deployed through 3-½ in. production tubing. The operation was to be performed from a semi-submersible platform, and the running and retrieving of the perforating guns would have to be accomplished without killing the well so that damaging completion fluids would not come into contact with the reservoir. Requirements for the job were that a safe method be used and that equipment and operational costs be kept at minimum so that a greater return on investment could be realized.Operational conditions included the following: 1. Perforation was to be conducted with the well in an underbalanced condition so that no formation damage would be sustained. 2. The operation had to be run from a semi-submersible platform that was set in a water depth of 430 ft. (2 nd job performed in a water depth of 968 ft.) 3. The gun assembly would have to pass through a 2.81-in. minimum ID.