During the last 30 years, in offshore Mexico, matrix stimulation treatments were designed and executed around pumping large volumes of fluids by a "bullheading technique," which comprised multiple stages of pre-flushes, acids, and solvents without adequate control of placement. The objective of these matrix stimulation treatments in the Ku-Maloob-Zaap carbonate formations fields is to remove drilling-induced damage and achieve maximum well productivity. This is a challenge because this formation is naturally fractured and presents high permeability, around 4-5 Darcies. The "bullheading technique" has been proven to be inefficient because the evaluation logs have shown non-uniform stimulated intervals.Recently, coiled tubing (CT) operations adapted a new procedure to improve the stimulation treatment's placement technique. However, the biggest concern was to determine if the chemical fluids had correctly stimulated the target zones. The initial solution was achieved by pumping radioactive tracers with the chemicals during the stimulation and an additional CT run performed to take a gamma ray (GR) log. This procedure has proven to be inefficient and time consuming.For first time in offshore Mexico, the innovative technique of combining coiled tubing equipped with optical fibers (CT-EOF) and distributed temperature survey (DTS) to acquire and record pressure and temperature data-which is compared with petro physical data in real time-to decide selective placement of chemical fluids in target zones, was implemented in a completed oil producer cased hole well in Campeche Bay. This innovative technique reduced operational time and eliminated the additional CT run while optimizing the placement of the stimulation fluids for improved well productivity. The information obtained from the DTS allowed informed decisions to be made on alternative lifting methods to improve the well productivity performance for this well.The job design, execution, and post-treatment evaluation of a matrix stimulation treatment in well M-432-where CT-EFO and DTS were combined-will show how the operation was optimized. In addition, the comprehensive analysis from DTS data was used to optimize placement of the stimulation treatment, the evaluation of effectiveness of the matrix stimulation treatment, the analysis used to identify the well productivity problem, and the benefits this new technique offers in the Ku-Maloob-Zaap carbonate formation.

In the Bay of Campeche, Mexico Marine operators have recently commenced the development of their high pressure, high temperature (HPHT) oil and gas fields in order to meet the high demand. These new developments present tough conditions for all aspects of well drilling and completion activities. They are particularly challenging for performing well intervention, which have driven operators, manufacturing and service companies to develop innovative strategies for servicing these fields. For HPHT well developments, electric line conveyed guns is the most common technique employed to perforate wells in the area, whether dynamic or static conditions. Nevertheless, coiled tubing (CT) deployed perforating has been recently employed as a reliable option in the following cases:Electric line is not a technically suitable option due to the limited magnitude of under-balance at which it can safely operate.Drag and buoyancy forces encountered in the wellbore are close to the operational limits of the cable.Wellbore tortuosity, tubular restrictions and well configuration render electric line unable to access perforation target depth. Initially, this paper discusses the workflow for performing technical analysis to develop safe and economical CT conveyed perforating operations for HPHT wells in offshore Mexico, which considers CT string design, surface equipment, well control equipment and associated downhole tools. It then presents case histories and lessons learned. And finally, provides conclusions and recommendations from the experiences gained for performing HPHT CT deployed perforating activities in Mexico Marine. Introduction HPHT define well conditions above what is considered normal levels of pressure and temperature. For Mexico Marine operators any well intervention with wellhead pressure (WHP) above 3,500 psi and bottomhole temperature over 150 oC (BHT) is considered HPHT. The Bay of Campeche is located at the southeast of Mexico in the continental platform of the Gulf of Mexico in front of Tabasco, Campeche and Yucatan coasts (Fig. 1). In 2004 Mexico Marine operators started to develop in the Bay of Campeche a significant number of fields that meet HPHT definition. In Mexico Marine HPHT fields, electric line conveyed gun is the most common technique employed to perforate wells. However, CT conveyed perforating has been recently proved as an excellent option in cases where electric line restricts under-balance magnitude for safe operation, drag and buoyancy forces encountered in the wellbore are close to the operational limits of the cable, and tubular restrictions and well configurations may be a concern to access perforation target depth. Mexico Marine HPHT Environment HPHT developments (Fig. 2) in the Bay of Campeche target Cretaceous (K) and Upper Jurassic Kimmeridgian (UJK) formations. Cretaceous is a naturally fractured carbonate formation ranging depths from 4,500 to 5,500 m with Porosity ranges from 3.0 to 5.0% and Permeability of 18 md. Upper Jurassic Kimmeridgian is a dolomitized carbonate formation in Oolitic banks from 5,000 to 6,000 m, where Porosity ranges 5.0 to 8.0% with Permeability from 20 to 40 md. The new fields under development are highly pressurized with bottomhole pressure (BHP) from 10,000 to 12,000 psi and BHT up to 190 oC. In surface, shut-in pressures from 6,000 to 8,500 psi have been recorded, and hydrocarbon production is composed by gas and oil from 27.0 to 48.0 oAPI. Drilling operations are performed by jackup rigs from eight-leg fixed platforms in water depths up to 60 m. Well deviation ranges 0 to 60 o, and jackup rigs are also the most common structures available for well completion and workover operations. These rigs have a limited crane capacity of 30 ton to lift and position CT string onboard.

World energy demand has led unconventional reservoirs to become a focal point for operators worldwide. In some regions, including North America, unconventional resources have been developed successfully, accumulating important experience and lessons learned in the process, allowing these resources to become important contributors to countries’ energy production. In an attempt to reproduce this effect in other regions, operators are also looking into important unconventional reservoirs outside North America. Currently the world’s third-largest shale oil and gas resources holder, Argentina has become a key focus for many operators initiating exploration and development operations. This brings many challenges to operators trying to take over this market as quickly, efficiently, and safely as possible. When developing unconventional reservoirs in the magnitude expected, one of the most important challenges for service companies and operators in Argentina is effectively grasping the global expertise, best practices, and lessons learned from these types of operations and adapt them to the local environment. This should reduce the learning curve experienced while starting a new development. A key component of these challenges includes all coiled tubing (CT) interventions involved in well completion; expertise in CT intervention is critical because of the risks concerning these operations, which include wellbore calibration, perforating, fracture plug drillouts (FPDOs), and sand cleanouts. Overcoming this challenge can translate into valuable time and cost reductions and allow operators to reach the efficiency that took years to attain in other parts of the world in much less time. Lessons learned and best practices incorporated from global experience, in addition to the local ideas, contributed to the implementation of CT interventions for the shale startup and beginning of the development phase in Argentina. Statistics and results from jobs performed in these reservoirs in its first year since startup reflect the changes and adaptations undertaken to successfully develop the shale resources in Argentina and to inform future plans for this rapidly evolving market.