A giant carbonate field offshore Abu Dhabi is being redeveloped using extended-reach-horizontal-laterals up to 20,000 ft with open hole un-cemented liner, drilled from artificial islands. Long horizontal wells provide significant profitability in unit development cost; however it is critical to ensure effective stimulation of the complete lateral to maximize reservoir recovery. Earlier, SPE171800 introduced an innovative liner design for long open hole horizontal completions, namely Limited-Entry Liner (LEL) that enables high rate aggressive stimulation by bullheading technique. This paper will present the field stimulation results of more than five LEL laterals ranging several-kilometers in open hole completions, demonstrating the impact of LEL stimulations in accelerating production and maximizing reservoir recovery. Several LEL horizontal wells were completed in low-permeability rock to enable high rate bullhead matrix stimulation. ExxonMobil proprietary software is used to design fit-for-purpose LEL that enables acid injection conformance along the lateral and at the same time creates deep-wormholes by high-velocity acid-jets through 3-mm/4-mm holes in liner base-pipe distributed non-uniformly along the lateral, compartmentalized with oil/water-swellable-packers. The execution of the stimulation campaign was made possible through the use of modularized-equipment packages installed on an ADNOC-vessel, utilizing a unique mechanism that locks the package components to frames installed to the vessel-deck. The stimulation package consists of 6×2000HHP pumps delivering up to 60bpm at 10,000psi. The liquid-additive system, 140bbl vertical mixing tank and more than 190,000gallon raw-acid storage tanks are fully automated to enable acid mixing and pumping on the fly at the desired rates, concentrations and recipes. In order to demonstrate the effectiveness of acid placement and effective stimulation across the entire lateral, real-time Fiber-Optic surveillance techniques (DTS-DAS) were utilized. The recorded thermal and acoustic profiles provided a qualitative and quantitative measurement of the effectiveness of the mechanical diversion delivered by the LEL design. These data will help in corroborating and fine-tuning the model used in lower completion design of maximum reservoir contact wells in future field development. Along with well performance and real-time surveillance, production/injection logging data demonstrates effective stimulation of the entire lateral. This paper presents field performance results from successful bullhead stimulation of extended reach horizontal well completed with LEL in low-permeability-reservoir. This paper also presents our first application of fiber-optic-DTS-DAS real-time-surveillance during stimulation and post-stimulation water injection. Advanced surveillance data demonstrated the success and effectiveness of the LEL completion and stimulation in extended-reach long horizontal open hole laterals.

The ability to intervene in extreme extended reach wells using conventional technology has lagged behind the ability to drill and complete them. This paper intends to describe how the physical properties inherent in carbon composite materials provide a means of deploying logging tools into such a well in combination with a high-performance tractor, and to document a case study where a total depth of 40,600 feet (ft) was achieved against a production flow of 6,500 barrels of oil per day (BOPD). Extending the distance that a toolstring may be conveyed into a horizontal well by means of tractoring devices is well established. The medium for the conveyance becomes the critical component of the system to both maximise the ultimate depth achievable and to ensure safe retrieval. Low friction, low weight and high strength of the rod all combine to reduce required tractor loading and ensure safe recovery. The rod rigidity confers exceptional depth accuracy and removes the potential of tool-lift at high production rates, allowing logging under conditions that are truly representative of commercial well operation. A well that was drilled to a depth in excess of 40,000ft measured depth, with a trajectory designed to maximise the contact between wellbore and reservoir, was completed with a limited entry liner. A total of 37 compartments with lengths between 700ft and 900ft were separated with swell packer assemblies along a horizontal section of 25,000ft. Critical information about the production flow, including toe/heel balance, had been unavailable because of the limitations imposed by the available intervention methods. The intervention was designed to fully exploit the physical properties of the carbon composite rod in combination with the most efficient in-well controlled tractoring technology available, and aimed to reach deeper than 40,000ft. Simulations based on previous experience showed that this depth would be achievable with the tractor chosen and further that this could be achieved even with the well flowing at rates of over 5,000BOPD. This meant that deferred production could be minimised along with waiting periods for flow stabilisation. The intervention was successfully concluded in a single operation, gathering production data from as deep as 40,600ft. Performance of both rod and tractor aligned with planning simulations with significant margin, indicating further performance enhancements in reach being readily achievable. Drilling of such extended reach wells from existing islands will reduce well counts, accelerate development and increase oil recovery by unlocking reserves from the tight rock and areas that are currently unreachable from existing islands and wellhead platforms. Technology solutions like carbon composite rod and high-performance tractors enable the operators to acquire production logs & perform well services effectively to maintain the life cycle of extended reach wells inaccessible with conventional solutions.

This paper describes advances in an integrated analysis workflow of Distributed Acoustic Sensing (DAS) and Distributed Temperature Sensing (DTS) for water injection profiling on a horizontal well, completed with Limited Entry Liners (LEL). The well is completed as an injector with Limited Entry Liner (LEL), MRC horizontal lateral made of 18 separated zones with packers, each with variable numbers of holes. DAS and DTS data were acquired on coiled tubing, over an acid stimulation period followed by a water injection period. Previous analysis of the dataset, SPE-203065, focused on DTS warm-back models and highlighted challenges in the process; the use of the DAS data was limited. Recent re-processing of the data using advanced acoustic signal processing techniques was performed to extract several flow characteristics. Both transient and steady state injection conditions were analyzed: High-definition low frequency slow strain DAS was extracted over the shut-in to injection transient to compute an initial injection velocity profile as well as a stage level injection distribution across the liners. During steady state flow, acoustic denoising algorithms were applied to the DAS data in order to generate a spectral noise log of high signal to noise ratio (SNR) for the detection of all major injection points. Video animations were generated of spectral noise logs over time, to evaluate the dynamic behavior of the injection profile from start to end. The warm-back DTS data was analyzed for a qualitative assessment of the injection Finally, a quantitative injection profile was computed, and the results were compared against a separate PLT log at both stage and nozzle levels. The results of the transient and steady state flow analysis converged and showed the highest water intake to occur over the heel-ward stages. The depths of highest rate of change in injection velocity, aligned with the strongest acoustic signals from the enhanced noise log. Inversely, the weaker acoustic outflow activities over the middle and toe sections aligned with the smaller velocity changes. The video animations showed a stable injection profile over time. The qualitative DTS analysis confirmed the overall DAS-based injection profile. The comparison with the PLT injection allocation highlighted clear differences in the profiles. These are being discussed, as well as the possible causes for the discrepancies. This analysis demonstrates the strength of an integrated DAS and DTS analysis workflow using both transient and steady state conditions. DAS array processing techniques enabled the extraction of high-definition transient thermal plumes, allowing for an early injection profile, which was further strengthened by high SNR spectral noise logging.

An extreme-performance polymer-locked wireline cable overcomes the conveyance challenges in tortuous wellbores, enabling the acquisition of high-quality production logging data in extended-reach drilling (ERD) wells. The use of this technology enabled an operator in the UAE to successfully evaluate the downhole production and reservoir properties in four extended-reach wells drilled from an artificial island. Production logging data acquisition using conventional wireline cables is challenging in such wells because of extreme cable tensions. This paper presents a case study about a novel approach of combining an extreme-performance polymer-locked cable and high force tractors to successfully convey production logging tools in an extended-reach well, where previous attempts with two conventional wireline cable types had failed. The new approach is based on analyzing the drag forces acting on the cable in the wellbore and modeling the tortuosity of the wells for determining optimal cable and tractor properties to minimize these effects. Based on this in-depth analysis, high-strength, torque-balanced, polymer-locked coaxial cable and high-force tractors with large wheels are selected for the job. With meticulous risk management and establishing a core team of key personnel, including field operations, the operator, and the product manufacturing center, this new technology is successfully deployed. Production logging tools are successfully conveyed to the maximum depth of 27,800 ft, and safely retrieved from the well. Excellent flowing and shut-in log data are recorded in a single descent, making it possible to accurately quantify zonal contributions from this horizontal lateral for the first time. Good tension profile with new cable shows the value of torque-balanced cables in high-tortuosity well profiles. The success of the job created confidence in conducting safer, more efficient intervention in maximum reservoir contact development wells. It demonstrates the value gained by deploying advanced high-strength polymer-locked coaxial cables in combination with high-force tractors.

A giant carbonate field offshore is being redeveloped using extended-reach horizontal laterals, up to more than 20,000 ft. with open-hole un-cemented liners, drilled from artificial islands. Previously, SPE171800 introduced an innovative Limited-Entry Liner (LEL) design that enables high rate aggressive stimulation of these wells by bullheading. These wells provide significant profitability in unit development cost, though it is critical to effectively stimulate the entirety of the long laterals to maximize reservoir recovery. Recently, Sau et al. 2019 presented our first application of real-time fiber optic surveillance during the successful stimulation of a water injection well with a 12,000 ft LEL lateral section. Fiber optic distributed temperature and distributed acoustic sensing (DTS/DAS) data were collected. Qualitative analysis of the real-time data were compared with a subsequent production logging tool (PLT) to confirm the effectiveness of the LEL completion and also the validity of the real-time fiber optic data. This current paper describes the detailed analysis of the DTS/DAS dataset collected and the information that can be extracted from it regarding the effectiveness of the well stimulation. Also presented here is how DTS/DAS can be used to monitor the completion performance during injection; quantitative DTS/DAS analysis provides detailed insight into the acid volume injection into each compartment as well as post-stimulation water injection profile over time and at different injection rates. Recommendations are made regarding how to use the data from future DTS/DAS enabled stimulation jobs to extract the most value from real-time measurements and how permanently installed fiber optic DTS/DAS systems can be used to monitor the health and performance of such extended-reach injection wells.