Haddad, Mohamed (ADNOC Offshore) | Rashed Al-Aleeli, Ahmed (ADNOC Offshore) | Toki, Takahiro (ADNOC Offshore) | Pratap Narayan Singh, Rudra (ADNOC Offshore) | Gumarov, Salamat (Schlumberger) | Benelkadi, Said (Schlumberger) | Bianco, Eduardo (Schlumberger) | Mitchel, Craig (Schlumberger) | Burton, Phil (Schlumberger)
Injection of drilling waste into subsurface formations proves to be an environmentally-friendly and cost-effective waste management method that complies with zero discharge requirements. It has now become the technology of choice in offshore Abu Dhabi.
The aim of cuttings reinjection (CRI) is to mitigate risks associated with subsurface waste injection and reduce cuttings processing time and cost. In order to meet these goals, a cuttings reinjection subsurface assurance methodology was developed to improve cuttings processing and continuously monitor drilling waste injection operations.
Preparing for CRI operations required extensive drilling cuttings slurry testing to minimize processing time and develop optimum particle size distribution to reduce cost and increase the injected waste volume. The improvements were accompanied by downhole pressure and temperature monitoring of the injection well, thus facilitating analysis of injection pressures. Fracture containment was verified through a combination of pressure decline analysis, periodic injectivity test, temperature survey, and periodic modelling for fracture waste domain mapping. A backup injection well was used also as an observation well to monitor the pressure signitures in the injection formation.
More than 1 million barrels of drill cuttings and associated drilling waste have been safely and successfully disposed of into a single injection zone of CRI well over three years of operations.
The cuttings reinjection subsurface assurance method optimizes grinded cuttings particle size distribution, detects and identifies potential risks to provide mitigation options to prolong the life of the injector.
The proactive subsurface injection monitoring-assurance program was built into the fit for purpose CRI injection procedure to continually avoid injecting any rejected hard material, improve and update the process as per subsurface injection pressure responses, thus reducing processing time and cost, mitigating injection risks, and extending the injection well life.
This paper presents the unique and technically challenging cuttings slurry properties design and pressure interpretation experience learned in this project; the enhancement of cuttings processing helped increase injection volumes and an in-depth interpretation of fracture behavior which behaved like a risk-prevention tool with mitigation options. Significant enhancement was developed in slurry treatment procedures to avoid injectivity loss and maximize the disposal capacity.
Ruzhnikov, Alexey (Schlumberger) | Banda, Maria Yanez (Schlumberger) | Malagon, Cecilia (Schlumberger) | Al-Wahedi, Khalid (ADMA-OPCO) | Toki, Takahiro (ADMA-OPCO) | Benygzer, Mhammed (ADMA-OPCO) | Singh, Rudra (ADMA-OPCO) | Alzate, Jose (ADMA-OPCO) | Kasem, Youssef (ADMA-OPCO)
From the start of the drilling campaign on the remote Satah Al Razboot (SARB) artificial islands located in United Arab Emirated (UAE) the operator used multiple optimization initiatives to enhance drilling performance and well delivery.
Even though the complexity of the wells increased over time, when extended reach drilling (ERD) envelop started to expand, with the implementation of optimization initiatives the well construction time significantly decreased. This paper describes the way of thinking and steps taken to boost the performance to the absolutely new level for the operator.
The main objective in actual harsh economic conditions was to drill the wells under the budget without jeopardizing well integrity, service quality and HSE. The ultimate goal was to decrease well construction time by 25%. To achieve this goal, several well construction optimization workshops were organized aiming to challenge and find improved drilling processes, operations procedures, tools, equipment and well design, as well as to have a clear plan on smooth expanding ERD envelop.
In addition with the workshop initiatives, an Operational Performance Improvement Plan was developed aiming to analyzed all operational opportunities to reduce time; a dedicated well engineering, subsurface and operations team was set up to lead the feasibility studies and ensure the implementation of the approved initiatives.
Implementation of all performance improvement initiatives required a balance between all involved parties. Every decision should be verified by multiple teams, included but not limited by drilling, equipment, completion, subsurface, production and intervention. Once the approval is obtained then the initiative is implemented and analyzed, taking into account increasing complexity of the wells and lesson learnt captured. At the same time not all the initiatives were implemented – some were rejected due to significant increase of service quality risk; some due to HSE associated risks. The implementation of the initiates and ideas contributed to the reduction of flat time, elimination of online operations, etc.
The manuscript describes the steps taken to drill extended wells within shorter time compare to standard deviate and horizontal wells. It highlights main challenges faced during implementation of the performance improvement plan and describes techniques and technologies used to overcome them.
Toki, Takahiro (ADMA-OPCO) | Benygzer, Mhammed (ADMA-OPCO) | Wahedi, Khalid Ahmed Al (ADMA-OPCO) | Anurag, Atul Kumar (ADMA-OPCO) | Singh, Rudrap Pratap Narayan (ADMA-OPCO) | Sayed, Mohamed I (ADMA-OPCO) | Ruzhnikov, Alexey (Schlumberger) | Cocagne, Michael Jason (Schlumberger)
Gathering of wireline data in Extended Reach Drilling (ERD) wells is still not a standard process, complicated even more by inclination and step out. This paper presents a case study of recording logs conveyed using an open hole tractor in a highly deviated section. The challenge was made more difficult because Water Based Mud (WBM) was required to allow the full suite of planned logs. The operation time that can be saved is up to four days.
The 8.5 in. pilot hole was designed based on the target and the sidetrack points for the mother hole. The inclination of the pilot hole was 63° and the wireline accessibility simulation based on offset friction factor showed that the open hole was not 100% accessible with Wireline Conveyed Logging (WCL) string. Therefore, an open hole tractor was selected to reach the required point. To minimize the risks for the logging operation, a six blade Polycrystalline Diamond Compact (PDC) bit, Rotary Steerable System (RSS) and Logging While Drilling (LWD) were used in the pilot hole to make a smooth trajectory and confirm wellbore conditions.
The logging operations were conducted smoothly and safely. It was observed that the actual results matched very well simulations, and the open hole tractor was required to convey the tools to the Total Depth (TD). The total tractoring length was 16,000 ft over the four runs, and there were no issues observed during the tractoring which confirms that the steps taken while drilling the section were correct and approximately four days of operation were saved by means of the open hole tractor as compared to Pipe-Conveyed Logging (PCL) operation. In addition, the mother hole length also was minimized to get proper sidetrack point from the optimized pilot hole trajectory and the potential total saving time would be more than seven days.
This paper also describes the optimization of well trajectories for pilot hole and mother hole and the gap related to planning from drilling and logging points of view, with aim to ensure 100% data gathering. The use of an open hole tractor for long interval in highly deviated well is the first time in the United Arab Emirates (UAE) and WBM conditions are non-standard operations which require significant amount of preparation during execution.
Toki, Takahiro (ADMA-OPCO) | Al Wahedi, Khalid (ADMA-OPCO) | Benygzer, Mhammed (ADMA-OPCO) | Kasem, Youssef (ADMA-OPCO) | Singh, Rudra Narayan (ADMA-OPCO) | Sookram, Neil (Schlumberger) | Cocagne, Michael (Schlumberger) | Banda, Maria Eugenia Yanez (Schlumberger) | Klein, Daniel Hunter (Schlumberger) | Wagner, Joris (Schlumberger)
After Cuttings Re-Injection (CRI) wells are drilled and cased over the targeted zone, the next step in the process towards finalizing the well is usually perforating the casing. Perforating guns can be deployed with the rig on location or rigless after the production string has been run in the well. Operations with the rig usually offer the benefit of being able to use larger guns with improved formation penetration and larger perforation tunnel size. The extra penetration helps bypass the damaged zone around the wellbore to get into the better permeability of the undamaged formation rock for improved injectivity. The larger perforation tunnel allows more contact with the formation and increased flow area, factors which also help improve injectivity. Rigless perforating generally requires smaller guns which can pass through the tubing, and therefore offer less formation penetration and smaller perforation tunnels. However, one of the major benefits of the rigless operation is the rig time savings, which can often be substantial.
Very good injectivity is a must for CRI wells to manage the large amount of cuttings that will be injected. Large diameter holes in the casing are necessary along with a high shot density for more holes, and 7″ perforation guns were required for the 9-5/8″ casing to achieve these characteristics for injection purposes. When large perforating guns are used, the tubing-conveyed perforating (TCP) technique is usually prefered over cable-conveyed guns because of possible cable damage from shock when the guns are detonated.
The TCP technique often requires more rig time however and usually results in more overall cost than for a wireline operation with a small number of gun runs. Another consideration for the CRI wells is that they are drilled by a new rig with a relatively inexperienced rig crew. Considering rig performance, using wireline for the perforating operation could therefore be more effective in reducing operating time. However, a number of factors have to be taken into account when preparing for perforating using longer, large diameter gun strings on cable, including gun string weight, shock on cable head when the guns are detonated and cable weak points. The shock forces for this case were modeled with special software and the necessary high-strength cable, shock absorbers and weak points were procured for the operation. Rig up limitations also had to be considered to manage the length and weight of the heavy string and a special sequence was prepared and implemented using an on-site crane.
The job was managed safely and efficiently in the single planned run, marking the first time this type of operation has been done in the country and this paper summarizes the process and the efficiency results.
Mehtar, Mohammed (Abu Dhabi Marine Operating Company) | Haddad, Mohamed (Abu Dhabi Marine Operating Company) | Toki, Takahiro (Abu Dhabi Marine Operating Company) | Gumarov, Salamat (M-I SWACO, a Schlumberger Company) | Benelkadi, Said (M-I SWACO, a Schlumberger Company) | Shokanov, Talgat (M-I SWACO, a Schlumberger Company) | Vizzini, Carla (M-I SWACO, a Schlumberger Company) | Mitchell, Craig (M-I SWACO, a Schlumberger Company) | Khudorozhkov, Pavel (M-I SWACO, a Schlumberger Company)
This paper examines the challenges, solutions and milestones of the hydraulic fracturing based cuttings reinjection (CRI) process implemented on two artificial islands offshore Abu Dhabi.
During the development of an offshore field from two artificial islands, disposing of vast amounts of drilling waste and cuttings, generated from almost 100 wells, presented a major challenge. The conventional skip-and-ship for onshore treatment and disposal was technically, logistically, and economically unviable and posed possible future environmental liability. After careful assessment, total containment of drilling waste on the islands through multiple hydraulic fractures in suitable formations, for permanent in-situ waste confinement, was concluded by the operator as environmentally and economically the only sustainable process.
Two CRI wells were planned on each island to accommodate an estimated 8 million barrels of drilling waste slurry expected to be generated at the islands. While CRI is a proven technology wherein cuttings are slurrified and injected into sub-surface formations, fracture injections have high risks too. Many failures are known in the industry, including well and formation plugging and waste breaches to sea-bed and near-by wells, with far-reaching consequences and liability to operators.
Considering the complexity of the multiple-hydraulic fracturing process that requires careful planning, execution, monitoring, and analysis, a comprehensive geomechanical study was performed to identify and characterize all potential injection formations to achieve successful long-term injection. This was followed by front-end engineering design (FEED), fracture simulations, CRI well design, surface facilities design, slurry simulations, and followed by careful execution.
Two CRI wells were drilled on each island. Specifically designed injectivity tests were performed on each well before commencing injection, followed by regular injectivity tests to continuously analyze fracture behavior. A carefully designed slurrification and injection process, incorporating detailed QA-QC at all process stages, was implemented that helped to avoid solids settling, fracture or perforation plugging, uncontrolled fracture propagation, or well integrity issues. About 500,000 barrels has been successfully injected to-date in two CRI wells with injection pressures as per FEED estimates.
The paper details also the proactive sub-surface injection monitoring-assurance program built into the CRI injection procedure to continually modify the process as per sub-surface pressure responses, thus proactively mitigating injection risks.
Periodical injectivity tests, model alignment studies, temperature logs, and fracture pressure analysis facilitated regular recalibration of the geomechanical model to define fracture-domain sizes, monitor fracture height growth, and estimate residual formation domain capacity as injection progressed.
The multiple-hydraulic fracture-based CRI process implemented first time in Abu Dhabi incorporates many unique features which can be applied in similar projects elsewhere. This paper also describes the downhole gauges for accurate pressure-temperature monitoring at perforations, a detailed slurry design, the particle-size distribution for slurry quality analysis and quality control, the sub-surface monitoring-assurance program and regular tests and recalibration studies.