When performing matrix-acid treatments, the goal is to stimulate the formation as deeply as possible, distributing the acid uniformly over the total zone of interest. Uniform distribution is even more important when intervals are long, horizontal, or several zones with natural fractures predominantly take the reactive fluid. In Italy's major oil-producing field, all of these challenges are faced. In addition, during production, asphaltenes form and are deposited in the well, making it even more difficult to distribute the acid evenly. Because the field is located in an environmentally sensitive area, all fluids need to be mixed and pumped using a zero-operational-risk philosophy. Some of the matrix-stimulation challenges were overcome as a result of the development of a novel emulsified acid that combines the practiced asphaltene-dissolving technique with proven acid-diversion technology. The environmental challenges are overcome by creating an oil-external/acid-internal emulsion, on-the-fly, just before the fluid is pumped downhole. This paper describes the engineered process of finding solutions to the challenges, beginning with laboratory testing to develop and optimize the solvent part of the innovative acid system. Further, an overview of how operational difficulties were resolved and how the innovative fluid system was applied is presented. The first section of the paper outlines laboratory testing, showing that an emulsified-acid system can be mixed with custom-tailored asphaltene-solving blends and provide the desired benefits for matrix acidizing, such as a slower acid reaction, higher base viscosity, and excellent emulsion stability in temperature. The second part of the paper explains the equipment setup used to create the acid system ready for field application in an environmentally sensitive area. The third part of the paper describes how the novel acidizing approach in its first field application boosted production to unexpected highs.

The largest active onshore field in Western Europe produces crude from 20 long horizontal wells from a naturally fractured carbonate reservoir. The produced crude deposited asphaltenes in tubing, openhole sections, and slotted liners. Over time, the deposition became so severe that it involved the reservoir fractures, affected well productivity, and caused a premature fieldproduction decline. Removing the formation damage, therefore, became a priority for appropriate field management.The injection of asphaltene inhibitors at packer depth reduced asphaltene deposition in tubing but did not protect the long openhole or the natural fractures from plugging. Bullheading or coiled-tubing (CT) solvent treatments were frequently performed with limited benefits.In 2009, an extensive asphaltene cleanout campaign was performed with more aggressive solvent treatments, covering almost 70% of producing wells. Continuous post-treatment-analysis improved the stimulation effectiveness and optimizing the dissolving fluids led to a production increase per treated well of 500 to 3,500 bbl crude per day. Unfortunately, the treatment techniques applied did not allow sustained production increase unless well interventions were frequent, up to bi-monthly.To reduce the treatment frequency, an emulsified-acid treatment was performed. The innovative emulsion, where acid was emulsified in solvent, provided a delayed acid reaction and allowed live acid to penetrate deeper into the formation. This allowed the flow pattern to be changed in a way such that the asphaltene deposition was slowed down, and the high well production was sustained over a prolonged period. This paper describes the history of the treatment methods, the extensive asphaltene-cleanout campaign performed, the post-job analysis, stimulation-treatment improvements based on field experience, and the final novel application of an emulsified-acid treatment that sustained a prolonged production gain of more than 10,000 BOPD and recovered initial well productivity.

In recent years, Underground Gas Storage (UGS) has earned itself strategic importance as it guarantees energy sustainability in markets suffering from unpredictable supply. Storage management is a complex activity which faces the challenge of combining the variability of daily commercial client requests along with the capability of the reservoirs to deliver. Gas production and re-injection activity requires standard core competencies of the oil and gas industry, however the process is fast paced as compared to conventional hydrocarbon production activity as time scales from data analysis to decision making is reduced to hours. Stogit Spa, an Italian gas storage company managing 8 depleted gas fields in Italy has implemented an integrated system that dynamically links databases, visualization tools and reservoir/well simulators in order to assist the management process. This system called PERSEO (PErformance Reservoir StoragE Optimization) is aimed at enhancing efficiency by utilising a piece of intelligent fields application. The large amount of data from the 270+ wells of STOGIT equipped with SCADA systems monitoring real time gas rate and well head pressure, provides information for production/injection management. The challenge has been to extract the maximum information from the available database and computerize the process of updating well/reservoir performance automatically. This allows for faster monitoring, analysis and prediction of future well behaviour. A workflow was realised to transform available real time data into calibrated models in the following two steps:*Design an algorithm capable of filtering stabilised gas rates and wellhead pressures for every injection/production period to extract data representative of the well performance*Automatic updating of well performance (IPR/VLP) model and matching the algorithm filtered data with theoretical and practica 1 models (back pressure C, n equation). This paper describes the outline of the implemented PERSEO system, details of the computerized workflow along with sensitivities and the results obtained. Introduction The concept of "intelligent field" is a promising scenario for the future of oil and gas industry. What is more or less foreseen today (Gomersall 2007, Murray et al 2006, Unneland et al 2005) is the idea of creating a higher automation level in the management of a production asset. The increasing amount of available data, among which real-time subsurface sensors, and the trust in the potential of the "digital" revolution are probably the main drivers of this belief. However the kind of automation required is something really peculiar with the oil industry, where we should always admit that we don't really know what our main asset - the reservoir - looks like. The intrinsic impossibility to directly measure, to "see" the reservoir, brings the petroleum engineer/geologist in the continuous interpretation of indirect data in order to feed more or less complex models. Going from data to models and from those to decisions is the concretization of the value of the whole petroleum engineering activity. Decisions are fastened and enhanced by a value-chain able to define from data a limited number of clear scenarios.