No abstract

Productivity enhancement of tight carbonate reservoirs (permeability 1-3 md) is critical to deliver the mandated production and to achieve the overall recovery. However, productivity improvement with conventional acid stimulation is very limited and short-lived. Tight reservoirs development with down spacing and higher number of infill wells can increase the oil recovery. Nevertheless, poor vertical communication (Kv/Kh < 0.5) within the layered reservoir is still a challenge for productivity enhancement and needs to be improved. First time successful installation of fishbone stimulation technology at ADNOC Onshore targeted establishing vertical communication between layers, in addition to maximizing the reservoir contact. Furthermore this advanced stimulation technology connects the natural fractures within the reservoir, bypasses near well bore damage and allows the thin sub layers to produce. This technology requires running standard lower completion tubing with Fishbone subs preloaded with 40ft needles, and stimulation with rig on site. This paper presents the case study of the fishbone stimulation technology implemented at one of the tight-layered carbonate reservoir. A new development well from ADNOC Onshore South East field was selected for implementation of this technology. The well completion consisting of 4 ½ liner with 40 fishbone subs was installed, each sub containing four needles at 90 degrees phasing capable of penetrating the reservoir up to 40 ft. While rig on site, acid job was conducted for creating jetting effect to penetrate the needles into the formation. Upon completion of jetting operation, fishbone basket run cleaned the unpenetrated needles present in the liner to establish the accessibility up to the total depth. Overall, application of this technology improved the well production rate to 1600 BOPD compared to 400 BOPD of production from nearby wells in the same PAD and reservoir. In addition the productivity of the candidate well improved by 2.5 times with respect to near-by wells in the same PAD. Currently, long-term sustainability testing preparation is in progress. This paper provides the details of candidate selection, completion design, technology limitations, operational challenges, post job testing and lessons learned during pilot implementation. In summary, successful application of this technology is a game changer for tight carbonate productivity enhancement that improves the overall recovery along with optimizing the drilling requirements. Currently, preparation for implementation of 10 pilots in one of the asset at ADNOC Onshore fields is in progress.

Fishbone Stimulation Technology was developed to increase the well productivity from the tight reservoir for maximum hydrocarbon recovery. Additionally, this technology was implemented in a thin reservoir where conventional stimulation techniques have not been effective and very risky for more aggressive stimulation technique such as hydraulic fracturing. The application of Fishbone Stimulation Technology was the first time experience representing a massive uncertainity. Thus, a multidisplinary team was estasblished, including members of different departments of the operator and contractors, to design the operational procedures, conduct risk assessment, contingency plans, technical requirements and technical limitations. this first implementation of the fishbone stimulation in ADNOC Onshore served as the benchmark and reference for other fishbone candidate wells in ADNOC Onshore and other ADNOC subsidiaries. The deployment of the equipment and the production results were a complete success overcoming the risks and previously mentioned uncertainities, closing some gaps from previous partial effective applications in other companies. The Fishbone stimulation technology will help to increase the well productivity via below mechanism in a well that is too risky to be hydraulically fractured and beyond the coiled tubing reach: Extension of the needles to connect natural fractures and vertical layers (for reservoir with poor Kv/Kh) Increase reservoir contact Sweep Efficiency of the reservoir

One of the main challenges in the oil industry is to develop tighter carbonate reservoirs. There are several methods to improve oil recovery (IOR), the adoption of Novel Lower Completions in horizontal wells can be one of the best tools to maximize reservoir contact and to control unwanted fluids (i.e., water or gas). It is especially important in carbonate reservoirs where most of the time it is imperative to provide additional stimulation in order to produce the reservoirs economically. The main objective of the presented work is to provide an alternative type of completion that creates better flow and stimulation distribution along the horizontal hole, In addition, the movable parts were eliminated to reduce the integrity risk while injecting the acid job stimulation. In carbonate reservoirs, the standard method to improve reservoir permeability is through acid stimulation utilizing coiled tubing to place acid into the reservoir rock and improve the flow within the near wellbore area. This technique is costly and time consuming. Furthermore, in the specific case presented, there is the constraint of limited number of coiled tubing units where many times acid stimulation is delayed due to this fact. Installing the mono-bore segmented completion provides the capability to perform the job without the rig, only bull heading the acid utilizing high pressure pumps. There are several options to install lower completions in the oil industry for horizontal wells. Smart liner is presented as an alternative to the conventional pre-perforated liner. The smart liner design was done with a proprietary software and consists of a specific number of small holes distributed along the horizontal section to distribute the flow and provide better stimulation placement at higher rates improving "worm holes" creation and extension. The lower completion is equipped with swellable packers to provide segmentation in the horizontal hole for future requirements if needed such as zones shut off. After the successful installation in a water injection well, water injection was initiated to define a baseline to compare with the results after the acid stimulation. The paper presents the lower completion design, the acid stimulation program and the results before and after the stimulation is done without rig on site. Initial results after the stimulation are showing more than twice the injection rate after the job. This job was done without the use of coiled tubing providing a better acid stimulation along the horizontal hole. The 4-½ inches mono-bore completion is the first time that was done in the Asset, creating new opportunities to improve the stimulation and injectivity / productivity of the wells and consequent future Field development.

Permanent down Hole Gauges (PDHGs) are typically run in combination with Distributed Temperature Sensing (DTS) cable with Wellbore Segmentation using Swellable Packers. The interpretation of the signals of the DTS/PDHG is complex, but it provides the possibility to identify change in production / injection profile along the completion and changes to the composition of produced fluids. Permanent down Hole Gauges (PDHGs) is a system enables the user to measure the reservoir pressure and temperature at single fixed point on real time basis. Distributed Temperature Sensing (DTS) is a technology which provides the user with a technique to measure the temperature in a well (from the surface to the TD of the well) distributed along the fibre optic line at any time. Several challenges were anticipated and measures were taken to minimize the risks of such implementation to ensure smooth deployment successfully.