One of the major challenges in underground gas storage wells in Italy is to maximize the sand layers exposure by drilling slanted or sub-horizontal wells through several shale bodies to obtain high gas rate performances during the production and the injection cycles. This challenge has a significant effect in selection of the completion technique in these wells, which require an effective and reliable sand control for long term, and open-hole and large tubular size to minimize friction losses.Until now, standard open-hole gravel packing was the common completion in a single sand body, however in presence of shales open-hole expandable screens with annular barriers and blanks between each section of sand is the only completion option, except in fine sand environment.In this paper, we present experimental data of shale stabilizer treated-brine and three open-hole gravel packing case histories from one UGS field in Italy. In the three case studies the wells were gravel packed using shale stabilizer treated-brine in open-hole made up of sand layers containing shale, without negative impact on completion time.

At a time when maximizing operational efficiency is needed more than ever, advancements in data processing and analytical capacity may provide a sustainable path for uncovering hidden correlations and other insights from one of the basic roles and responsibilities of any surface logging services provider. This paper showcases a side-by-side comparison of two gas extraction devices and how they influence gas readings and, eventually, total gas measurement related to well control operations monitoring. Although the trend analysis from gas reading values is imperative for pore pressure predictions and other classical readings, this paper negates its use for lower explosive limits (LEL) by using laboratory methods paired with a study in the field. The apparatus used to extract total gas in water-based mud was a constant-volume, constant-temperature and constant-flow system. The detector used to measure the total gas concentration was a flame-ionized detector (FID) system. The influence of gas extraction devices on gas data is crucial for the determination of total gas. Conditions affecting gas readings have been explored at length, and they include gas extraction temperature, mud flow rates, gas flow rates, and drill rates (i.e., rate of penetration). Due to the development of analytical capacity, the extraction method and the analysis devices are compared in this paper. Wellsite total gas monitoring, which usually provides common wellsite total gas values, has been heavily analysed regarding what it fundamentally represents. Total gas also helps operators to harness their data and use it to identify process safety indicators, as well as other environmental emissions applications. Estimates of total gas concentration in the drilling fluid, as detected by a gas extraction device, can vary, based on the device type. This paper shows how the different extraction methodologies fit into well safety operations monitoring and process safety requirements to better evaluate and define new risk communication and safety practices in the industry.

Cement-sheath integrity is fundamentally important for well integrity and helps to ensure that the asset is operated safely and economically. If the cement sheath is damaged during well operations, it could lead to interzonal communication, annular pressure, and casing damage. Remedial jobs are then necessary to fix the problem and continue well operation. In some cases, it might not be economical to fix the problem, leading to well abandonment. The challenge to cement-sheath integrity is caused by the stresses resulting from change in pressure and temperature during well operation. Examples of wells that could be subjected to changes in pressure and temperature are deepwater, high-pressure high-temperature (HPHT), gas storage, steam injection, and geothermal. Gas storage wells in Italy are addressed in this work. An integrated, intelligent, and interventionless solution has been applied to solve the zonal-isolation challenges in such wells. The well events during the life cycle were integrated into the analysis and a cement sheath was designed and tested so that it was not damaged. Safety considerations were built into the design procedures based on the teachings of designs of other materials. This design procedure helped the cement sheath withstand cyclic loads, which could be significant in gas storage wells. During well operations, if the stresses on the cement sheath exceed the design limits, the cement sheath could be damaged. The initial damage could be in the form of small cracks and micro-annuli. If these damages can be fixed immediately and without intervention, then the formation fluid can be prevented from entering the annulus. Intelligent features were built into the cement sheath so that small cracks and micro-annuli could be automatically sealed if formation fluid enters the annulus. The integrated, intelligent, and interventionless zonal-isolation features of the solution offer a unique opportunity to prevent the annular pressure buildup if the cement sheath inadvertently fails. This solution has been implemented in a number of wells and is described in this work. The job implementation and subsequent results during the life of the wells have been successful. The unique features of the solution discussed and presented in this work is a game-changer and should help the industry solve a pressing problem and operate wells safely and economically. Introduction Storing natural gas during times when the demand is low and using it when the demand is high is a common industry activity. This procedure is followed in a number of countries around the world. The inherent nature of the process employed causes change in pressure and temperature during gas injection and then during gas production (gas withdrawal). It is important to maintain cement-sheath integrity so that the injected gas is contained and does not flow up the annulus to the surface or to another zone. Most of the gas storage wells are located close to the end customer. Therefore, from a health, safety, and environmental aspect it becomes extremely important to contain the injected gas and prevent leakage. Though best practices were used, zonal isolation was a challenge in the wells that were cemented before the techniques discussed in this work were applied. As shown in Fig. 1, 63% of the wells in Field B showed sustained casing pressure (SCP). This number was lower in Field A and C; however, SCP was still in the double digits. As a result, a campaign was undertaken to investigate the challenges and improve the reliability of zonal isolation.