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The case studies performed in the Middle East and South Asia region shared in the paper reflect the requirement of production/injection enhancement in challenging downhole conditions. Larger tubing diameter, limitations of minimum ID to deploy bigger OD tools, low bottom hole pressures, and requirement of high annular and jetting velocities are often demanded in CT clean-out operations. The advancements in coiled tubing metallurgies to intervene in complex wellbore geometries and the precision of downhole simulators to predict on-site scenarios have put more pressure on the efficiency of downhole tools in production enhancement services. Thus, the case studies required a tool that could overcome the barriers offered by incumbent technologies. It is confirmed from laboratory tests that a standoff of eight times the orifice diameter and fluid velocity of 200 ft/sec is required to remove moderate to hard deposits from wellbores. Conventional jetting tools have a standoff distance of more than 40 times and fluid velocities are far below 200 ft/sec thus objectives of CT intervention are often compromised. Moreover, the effectiveness of conventional tools for critical matrix in the stimulation operations is barely minimum as the jetting effect diverges from the jetting stream. A new type of fluidic oscillator was utilized in the case studies. Unlike pulsating effects created by 1st generation of the fluidic oscillators, the SFO type oscillator had triple jetting action namely, Helix jetting, Pulses Jetting, and Cavitation jetting which was equally effective for in-wellbore and near- wellbore regions. Paper also explains the working mechanism of the tool and demonstrates its ability to remove the skin in the critical matrix The results of the clean-out with SFO technology were beyond expectations. It reduced the operating times to two-thirds of conventional operations, which led to cost savings in all the case studies by an average of 35%. Moreover, it increased the efficiency of treatment fluids which resulted in the reduction of waste of additives, and the requirement of extra efforts to dispose of excess materials at wellsite. Also, jetting effectiveness caused an increase in production/injection from 30%- to 250% This is the first technology that uses cavitation jetting in oilfield services and the first to use aforesaid jetting actions altogether in one tool. The technology adopted in the case studies doesn't have moving or rotating parts, thus eliminating the requirement to pull CT out of the hole for redressing and can perform long operations in one go. It doesn't depend on the centralization of the tool as the jetting effect is passed via kinetic energy through submersed fluids, thus can target deeper depth without limitations of the standoff. It allows a higher flow rate of liquid and gas, thus offering higher energies for clean-out and stimulation operations.

Clean out using coiled tubing is the second largest application of coiled tubing after nitrogen kick-off. The advancements in coiled tubing metallurgies to intervene in complex wellbore geometries and precision of downhole simulators to predict on-site scenarios require more efficiencies from end tools that evolved from simple jetting tools to rotating jetting heads. The objective intended in the case studies performed in the Middle East and South Asia was to perform cleanout in scenarios where incumbent tools had failed in the past. The impact of jetting action in cleanout operations decreases with an increase in stand-off distance. It was confirmed from laboratory tests that a standoff of eight times the orifice diameter and fluid velocity of 200 ft/sec is required to remove moderate to hard deposits from wellbores. Conventional jetting tools have a standoff distance of more than 40 times and fluid velocities are below 200 ft/sec thus objectives are often compromised. A new type of fluidic oscillator was utilized in the case studies discussed in the paper. Unlike pulsating effects created by 1st generation of the fluidic oscillators, the SFO type oscillator had triple jetting action namely, Helix jetting, Pulses Jetting, and Cavitational jetting. The result of the clean-out with SFO technology was beyond expectations. It saved cost in all the case studies by an average of 35% if had been performed with incumbent technologies and increased production/injection from 30% - to 250% of the original value. Moreover, it reduced the operating times to two-thirds of conventional operations and increased the efficiency of treatment fluids which resulted in the reduction of waste of additives and extra additives to dispose of excess materials at wellsite. This is the first technology that used cavitational jetting in oilfield services and the first to use aforesaid jetting actions altogether in one tool. The technology adopted in the case studies doesn't have moving or rotating parts, thus eliminating the requirement to pull CT out of the hole for redressing and can perform long operations in one go. It doesn't depend on the centralization of the tool as the jetting effect is passed via kinetic energy through submersed fluids, thus can target deeper depth without limitations of the standoff. It allows a higher flow rate of liquid and gas, thus offering higher fluid velocities to perform an effective cleanout.

The paper presents the design and successful application of an ultra-low invasion non-damaging spacer system followed by nano-silicate based ultra-light cement with high crush strength to produce a competent cement sheath and ensure zonal isolation. The solution was applied in 7inch liner cementing of the candidate well where operator slightly increased the mud weight after gas kick during 8.5inch open hole drilling and encountered total losses. The job was executed with operational optimization and zonal isolation was achieved. The severe-to-total losses (exceeding 200 bbl/hr) were experienced during drilling and liner running. Consequently, circulation could not be established before job. The ultra-low-invasion non-damaging spacer was designed to create a thin, impermeable shield over the pores and micro-fractures of weak, and under pressured formations through differential pressure. It helped to resume circulation and cement pumping even when equivalent circulating density was exceeding the fracture pressure. The 11.6 ppg nano-silicate based high-crush resistant slurry prevented post-placement losses due to early compressive strength development and provided competent cement bonding. The fluids rheology was optimized, and pumping parameters were adjusted to maintain the primary well control during the cementing operation without compromising displacement efficiency. The technology was successfully implemented in the 7" liner cementing of the candidate well where cement evaluation was performed using sonic tools. The cement evaluation confirmed the zonal isolation along the open hole section. The proposed solution helped operator to ensure well integrity in troublesome lost circulation zones which posed well control challenges. It was later validated on four additional wells where the job was executed in similar environment and complete cement coverage was achieved in the section. The spacer system is found to be compatible with all common drilling fluid systems and can bypass the narrow restrictions of liner hanger thus offering an additional value over the conventional loss control fibrous materials. The deposited barrier on fluid-rock interface lifts off with the inflow of the well, eliminating the need for acidizing or other matrix stimulation treatments. This helped in formation impairment and simultaneously reducing time to first production. Additionally, nano-silicate based slurry having high-crush resistant lightweight additives maintained stable slurry with good fluid stability, high early compressive strength and improved bonding. Currently, well is open to production with no zonal isolation or cement integrity issues. The proposed solution will help operators to effectively control losses and enhance zonal isolation in narrow pressure window while achieving the planned cement height along with a competent cement bond. The operators can also avoid the money and time on expensive remedial operations.

Cementing of production casing in the Northern Iraq poses challenges to the cement sheath integrity due to mechanical and thermal stresses induced in the well life. The problem is further aggravated due to narrow window between pore pressure and fracture gradient. The acid-prohibitive cement system with improved mechanical properties was developed to mitigate the effect of induced stresses. The job was executed with operational optimization and zonal isolation was achieved. Based on the operator's well testing and multi-stage high-rate well stimulation plan, the stress modeling was carried out to determine the optimum mechanical properties. The 19.6 ppg heavyweight cement system with a flexible thermoplastic polymer was designed to achieve the required Young's modulus and Poisson's ratio. Since the density and friction pressure hierarchy could not be met due to the narrow window between pore pressure and fracture gradient, therefore, the slurry rheological properties were optimized for effective mud removal. The pumping parameters were adjusted to maintain the primary well control during the cementing operation without compromising displacement efficiency. The approach was implemented without any operational issues in the 9-7/8" production casing and 7" liner cementing. Following the job completion and waiting-on-cement time, the 9-7/8" casing was successfully pressure tested with a surface applied pressure of 2,000 psi and a well fluid of 1.78 SG. The isolation scanner cement evaluation confirmed the zonal isolation along the open hole of both the 9-7/8" intermediate casing and the 4½" production liner. Finally, the multi-stage high-pressure stimulation operations were performed during the completion/testing stage with no sign of communication between the different zones. The application of heavyweight acid prohibitive flexible slurry helped the operator to isolate the different zones of interest that were less than 10 m apart and retained the integrity of the seal throughout the high-pressure stimulation operation. Well is open to production without any annular pressure, thus, saving the operator's time and cost on the remedial cementing operations. The proposed solution will help operators to ensure long-term zonal isolation in the HTHP wells which are subjected to dynamic pressure and temperature changes in the post slurry placement phase. The operators can also avoid the time and money on expensive remedial operations.

The operation of bypassing the existing borehole by placing a kick off cement plug has historically been very well established and long-standing technique. Although placement of a cement plug appears to be a routine and relatively simple job, the instances of kick off plug not fulfilling the desired purpose are quite frequent requiring same degree of planning as primary cement jobs. Traditional cement slurry systems for sidetracking have been focused on the development of compressive strength by reduced water content. These cements exhibit low resistance to impact and toughness requiring multiple attempts to side track the well. An industry average for kick-off plugs is 2.4 attempts per kick-off, with 24 hours rig time associated with each attempt.This paper describes the engineered slurry system that incorporates unique properties of higher impact resistance, fracture toughness and load bearing capacity which resulted in slow ROP and sidetrack in 1stattempt. The main conclusion will be supported by case study at the end of paper.