A Novel Approach to Uniformly Acid Stimulate Carbonate Tight Formation Utilizing Multi Jetting Tool Technology

SPE Annual Technical Conference and Exhibition

et al. 2021

A case study is presented detailing the methodology used to perform the clean-out operation in a water disposal well of Khurmala Field, Kurdistan Region of Iraq. Untreated disposed water caused scaling and plugging in perforated liner and in the open hole that eventually ceased injection. Multiple attempts and investments were made in recent years to resume access to the injection zone using high-pressure hydro-jetting tools coupled with acid treatments. However, these attempts yielded futile efforts. Before proceeding with the decision of workover, it was decided to go for one final attempt to regain wellbore access using Fluidic Oscillator (SFO). Fluidic Oscillator (SFO) having pulsing, cavitation and helix jetting action was used in combination with a train of fluids consisting of diesel, 28% HCl and gel. The clean out was performed in stages of 10m, to clean the fill from 1091m to 1170m. Since the well bore was initially isolated from the injection zone, the cleanout was conducted with non-nitrified fluids. As the cleanout progressed and access to the liner and open hole was regained, the circulation of insoluble fill to surface required a lighter carrying fluid. Nitrification, volume of the fluids, batch cycling, and ROP were designed considering the downhole dynamic changes expected during each stage of the operation. The combination of SFO, the thorough selection of treatment fluids and the accurate downhole hydraulics simulations pertaining to different stages of the operation offered an effective solution and regained the connectivity between the wellbore and the injection zone. The injection rate of water increased from 0 bpm at 700 psi to 15 bpm at 200 psi. Throughout this operation, the SFO helix, cavitation, and acoustic pulse (alike) jetting proved to be more effective than other single acting rotating jetting tools. Also, Environmental impact was reduced by eliminating the need for a rig workover operation. The matching of the injection pressure when the well was first completed and the post job value indicated that the complete zone was exposed and scale deposits were removed from the critical matrix or bypassed. SFO has an effective jetting near wellbore region, while the kinetic energy transferred via fluid makes the impact stronger in the deeper region. Internal mechanism of the tool allows it to handle high pumping rate and pressures, external finishing offer multi-port orientation of outflow that allows targeting the fill in desired directions. Presently the SFO used in the case study is the only technology that has pulse, cavitation, and helix jetting structure. Also, since the tool does not require redressing, it proves to be an efficient, safe and cost effective alternative

Adaptation of Technologies Making Clean out Operations Environment Friendly and Cost Effective - Converting Failure into Success Using New Type of Fluidic Oscillator

Ahmed

Khoshnaw

SPE Annual Technical Conference and Exhibition

et al. 2021

Is Fluidic Oscillator a Game Changer in Improving Well Productivity? An Analysis with Case Studies

Khokhar

Day 3 Wed, November 02, 2022

Elmoneim

et al. 2022

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.

New Type of Fluidic Oscillator Made Clean Out Operation Environment Friendly and Cost Effective – A Case Study that Converted Failure into a Success

Ahmed¹,

Khoshnaw

Day 3 Wed, February 23, 2022

et al. 2022

Untreated disposal of effluent water has the potential of scaling and plugging the in and near-wellbore regions. A case study and methodology adopted for the clean-out operation of water disposal well of Khurmala Field of Iraq is analyzed in the paper. Previous attempts of clean-out using high-pressure hydro- jetting tools along with acid treatment proved futile effort. As last resort, Fluidic Oscillator (SFO) was deployed for clean-out to regain access of TD and plugged fracture network before the eventual decision of work-over is made. Combination of SFO having pulsing, cavitation, and helix jetting action in conjunction with train of fluids consisting of diesel, 28% HCl and gel were utilized. The operational sequence of clean-out was in stages of 10m to clean 79m interval, comprising of slotted liner and open hole, filled with detritus. Low bottom pressure required a dynamic approach for treatment-fluid nitrification based on the success of clean-out and access to liner and open hole. Annular velocities required nitrification once the slotted liner and open hole were open for in-take. Rate of penetration, sequence and volume of fluid-trains, nitrification, and batch cycling were designed in accord to changing downhole dynamics during clean-out. A thorough investigation of detritus, designing of fluids, the accuracy of downhole hydraulics, and application of SFO proved to be an effective solution. It regained access to TD and connectivity between the wellbore and the injection zone. Injection increased from none to 15 bpm at 200 psi. The combination jetting effect of SFO (acoustic pulse (alike), cavitation, and helix) demonstrated to be more effective than rotating jetting tools. Moreover, the merits of operational efficiency supplanted conventional operations and environmental impacts were considerably low in terms of operating time, spent additives, and avoidance of work-over operation. The matching injection parameters post-operation with native parameters post-completion indicated that detritus is removed from wellbore and damage from the critical matrix is removed/bypassed. Currently, SFO is the only technology that has pulse, cavitation, and helix jetting structures. It has an effective jetting for in and near wellbore region while the kinetic energy transferred via fluid makes the impact stronger in the deeper region. The internal mechanism of the tool allows it to handle high pumping rate and pressures while external finishing offers multi-port orientation for outflow that allows targeting the fill in desired directions. The tool does not require redressing, thus it proves to be an efficient, safe, and cost-effective alternative