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AlJallad, Osama (Ingrain A Halliburton Service) | Dernaika, Moustafa (Former Ingrain A Halliburton Service) | Koronfol, Safouh (Ingrain A Halliburton Service) | Naseer Uddin, Yasir (Ingrain A Halliburton Service) | Mishra, Prasanta (Kuwait Oil Company)
The evaluation of carbonate cores is a complex task because of the inherent heterogeneities that occur at all length scales. Rock properties may be defined differently at different scales and this introduces a challenge in capturing the heterogeneity in a single rock volume. This research work studied whole core samples using multi-resolution imaging and advanced computations. The samples could not be directly measured by conventional techniques due to their fractured state and complex nature. The cores are Mid Cretaceous in age, derived from a giant oil field in the Middle East and are predominately composed of limestone with complex paragenetic history.
The core samples were first imaged by X-ray dual-energy CT in 3D at a resolution of 0.5mm/voxel. The whole core CT images revealed extreme heterogeneity along the sample lengths and showed varying distribution patterns of high and low-density textures. The selected plugs from those density textures were acquired to accurately represent the different flow phases in the whole core samples. The plugs were fully characterized by high-resolution X-ray CT images at 40 μm/voxel, thin-section photomicrographs, poroperm measurements and Mercury Injection Capillary Pressure (MICP). These analyses provided a detailed understanding of the geological and petrophysical variations within the different density textures in the whole core samples. Simultaneously, smaller-scale subsamples were obtained from the different porosity regions in the plugs and scanned at higher resolutions down to Nanoscale at 0.064 gm/voxel.
The measured plug porosity and permeability data provided accurate results in the low and high-density regions in the whole core samples. This data was then upscaled to the whole core images by populating the individual data in the different textures and solving for the Stokes equation using the Lattice Boltzmann simulation. The upscaling process accounted for the varying fractions of the flow units in the sample, their interaction and their effects on the overall whole core properties.
The dual-energy CT scans along with core visual inspection, thin-section photo-micrographs and mercury injection pore throat size distributions (PTSD), demonstrated that each density region had similar geological and fluid flow characteristics throughout the core intervals. The upscaled poroperm data for all the core intervals gave a linear trend with a clear increment of porosity and permeability as a function of the low-density phase in the core. The permeability KV/KH anisotropy ratios were digitally computed for all the core intervals and were found to vary from 0.44 up to 0.94, which reflects the relative presence and distribution of the high and low-density regions in the reservoir core samples.
The digital analyses of the data together with the effects of heterogeneity distributions in the core provided an improved understanding of the geological and petrophysical properties in these complex reservoir rocks that would not be possible by conventional methodologies. The analyses were carried out at the pore scale and the core scale, which would lead to more robust reservoir engineering applications and petrophysical modeling of such complex reservoirs.
Water conformance is a common challenge in oilfield industry especially in water flood and active water drive reservoirs where water production has a significant impact on production economics, oil recovery and facilities constraints. Water shut-off (WSO) is an essential solution to delay or minimize water production however effectiveness depends on treatment efficiency. This abstract will demonstrate extensive mechanical and chemical WSO experience in horizontal drilled wells completed with passive Inflow Control Devices (ICD) completions, with case histories from North Kuwait giant water aquifer reservoir.
The main challenge during water conformance treatment is the proper diagnosis and the full understanding of the water flow profile; accurately identify the water source as well as reservoir understanding will help selecting the efficient WSO mechanism, which is crucial for a sound decision making considering the associated cost and the operational complications. Understanding reservoir geology, Integration of inflow profiling via Horizontal PLT and new technologies of water saturation logsare key to accurately identify the water source (heal, middle or toe side) and by turn WSO mechanism. This is done in integration of multidisciplinary domains of G&G, production and reservoir engineers and operation teams.
Mechanical WSO using inflatable packers' technologies were applied for isolating the toe side, while chemical WSO technologies used for heal side isolation in the open-hole passive ICD completions. Rig-less shifting of ICD sleeves used where active SSD-ICD's completion installed. The statistics of executed WSO results of many case histories have shown relatively good success ratio represented in reducing water cut from 80 – 90% down to 20 – 70%, increase oil production rate from 200 bopd up to 3000 bopd in some wells depending on water source. Furthermore, WSO enabled bringing some inactive high-water wells back to production. This helps extending well-life and by turn maximizes ultimate hydrocarbon recovery. Also, reducing the total water production to facility allowed increasing production of some other wells producing to same facilities. As key learnt lesson; managing the produced liquid rate and drawdown post WSO is essential to maximize the benefit of WSO and delay sharp increase of water cut.
WSO solutions are in constant improvement. Integrating reservoir characterization, fluid inflow profiling and proper selection of WSO technique is crucial for any successful WSO decision. WSO became a common practice to maximize the oil recovery factor from Lower Burgan reservoir of North Kuwait fields.
Centeno, Manuel (Schlumberger) | Krikor, Ara (Schlumberger) | Herrera, Delimar Cristobal (Schlumberger) | Sanderson, Martin (Schlumberger) | Carasco, Anant (Schlumberger) | Dundin, Alexander (Schlumberger) | Salaheldin, Ahmed (Schlumberger) | Jokhi, Ayomarz (Schlumberger) | Ibrahim, Sameh (Schlumberger) | Wehaidah, Talal (Kuwait Oil Company)
The complexity of drilling highly deviated wells in Kuwait drives the need for step changing in the well construction mindset, where severe to complete loss of circulation in Shuaiba formation significantly deteriorate the shale layers in Wara and Burgan formations leading to uncontrolled wellbore stability events. Casing while drilling (CWD) and two-stage cementing with a light density cement slurry were introduced as a technology system to drill the highly deviated complex wells through unstable and highly fractured formations. Fit for purpose engineering processes, advanced software solutions, a tailored bit and a bottom hole assembly dynamically simulated for drilling stability and directional tendency behavior were designed. A special light density cement slurry with high compressive strength was also designed to tackle the lost circulation issues when cementing the casing string. The paper will describe how the technologies can work as one system to solve complicated wellbore problems and address the problematic challenges of drilling unstable shales and fractured formations in the same section of the wellbore. This strategy enabled a significant time saving compared to drilling the section conventionally, removing Non-Productive Time (NPT) resulting from additional trips, cement plugs, stuck pipe, and subsequent sidetracks.
The characterization of the clastic Zubair reservoir is challenging because of the high lamination and the oil properties change making the conventional saturation technique uncertain. A new workflow has been recently established in the newly appraised wells which has involved advanced petrophysical measurements along with the fluid sampling. The new technique has led to identify new HC layers that were overlooked by the previous techniques, thus adding more reserves to the KOC asset.
Because of the high lamination of clastic Zubair formation and the change of the oil properties, the dielectric dispersion measurement was integrated along with the diffusion-based NMR to identify new oil zones that has been initially masked by the resistivity-based approach. The new approach has also provided details on the oil movability and the characterization of its property. As the newly identified layers were identified for the 1st time across the field, the fluid sampling was conducted to confirm the new findings.
The advent of a new logging technology from a multi-frequency dielectric technique deployed over the formation has independently pinned down the HC pays over the Zubair interval, including a new zone below the water column. The zone was initially identified as heavy Tar zone. The advanced diffusion-based NMR was thus conducted and integrated with Dielectrics which has demonstrated the movability of HC using the diffusion-based NMR approach over the newly identified zone. A fluid sampling was later performed which has confirmed the new finding. The new identified zone was initially overlooked by the previous interpretation and extensive modeling over the entire field. The seal mechanism was also explained by taking advantage of the high-resolution dielectric dispersion measurement (mainly the low frequency), which has been also supported by the Images interpretation. This new approach has added an incremental oil storage over the field.
Al-Enezi, Badriya (Kuwait Oil Company) | Liu, Peiwu (Schlumberger) | Liu, Hai (Schlumberger) | Kanneganti, Kousic Theja (Schlumberger) | Aloun, Samir (Kuwait Oil Company) | Al-Harbi, Sultan (Kuwait Oil Company) | Al-Ibrahim, Abdullah (Kuwait Oil Company)
A recent study showed that Tuba reservoir, a limestone-rich formation, has the highest oil in-place of all upcoming reservoirs in North Kuwait. This tight formation has three main layers - Tuba Upper (TU), Tuba Middle (TM), and Tuba Lower (TL) with several reservoir units alternating with non-pay intervals. The reservoir units contain significant proven oil reserves; however, production performance after conventional acid fracturing treatments has been historically subpar. As part of new development plan, two horizontal wells, one in TU and one in TL were drilled to evaluate the production potential of a new completion strategy and technologies.
This paper presents one such technology, a single-phase retarded acid system used as a pilot project study. In contrast with previous conventional emulsified acid systems, the single-phase retarded acid minimized tubing friction, thus enabling high pumping rates for the entire treatment. Alternating with the acid system, a viscoelastic surfactant-based leakoff control fluid system allowed the acid stages to reach deeper into the formation. To aid, degradable fiber technology was pumped in several stages to achieve near-wellbore diversion and further control leakoff into large natural fractures, thus improving the stimulated reservoir volume. These fibers are designed to completely degrade with time and temperature after the treatment. Delivery of the complex acid fracturing treatment was optimized in real time for each stage based on bottomhole pressure trend and response.
Combining a new single-phase retarded acid system with chemical diversion technology has proved to be effective in maximizing lateral coverage and etched fracture half-length. Post-treatment evaluation of TU horizontal well revealed the initial production was as much as 150% higher than offset vertical wells after conventional treatments with gelled acid and as high as 100% higher than a previous multistage horizontal well treated with emulsified acid. The TL horizontal well was just put into production recently and is showing encouraging results considering the lower reservoir quality compared to TU formation.
The success of this technique and technical combination delivered breakthrough results for this region and has engaged new interest in developing the Tuba reservoir.
Global oil demand has led to the development of new smarter drilling, completion, reservoir management technique and technology to optimize reservoirs production. The production of Kuwait Oil Company (KOC) has reached 3 MMBOPD and KOC’s 2030 vision is to boost the production to 4 MMBOPD. In order to achieve this vision, KOC has started several technical projects and development plans. One of these projects is the North Kuwait Integrated Digital Oil Field (NK-KwIDF) a full-fledged Field project implemented in KOC.
This Paper will discuss the scale, complexity, technology used, and advantage of using the NK-KwIDF. The North Kuwait (NK) asset has five fields, around twelve hundred active wells, and seven Gathering Centers (GCs). A complex network of pipeline, trunk line, and manifold are used to connect these twelve hundred wells to GCs. In order to optimize the production from NK every barrel of production opportunity has to be considered by optimizing suitable wells and minimizing downtime from each field, resulting the development of an extensive surface network model. The extensive surface network model takes into consideration of each and every details of field e.g. pipelines, manifolds, details of GCs and wells. For each and every well in NK assets a well model is prepared considering all PVT parameters, completions, and surface co-ordinate and finally connected to surface network model with all piping information.
Once the extensive surface model was prepared, several integrated workflows were developed in order to efficiently run the surface model and analyze the output from the run. Some of these workflows are ESP Optimization and ESP Analysis workflows, which have capability to identify the Oil Gain Opportunities and diagnose ESP performance. The identify opportunities are logged into ticketing system, which monitors the life cycle of the opportunity right from the identification till implementation into the field for Oil Gains.
The full-fledged development of NK-KwIDF took almost 3 years from the day it was started, as a pilot project with 133 wells. When an excellent result in terms of production optimization and downtime minimization was recorded from the pilot project, the pilot project was expanded to full-fledged field project. The NK-KwIDF project gave an outstanding result of Oil gain from well level as well as Network level optimization. It established an excellent reputation in the oil industry where it was a source of attraction for many NOC’s and IOC’s to visit and follow the flag ship for their development and implementation of digital field technology.
Al-Ghnemi, Mohammad (Kuwait Oil Company) | Ozkan, Erdal (Colorado School of Mines) | Kazemi, Hossein (Colorado School of Mines) | Al-Murayri, Mohammed (Kuwait Oil Company) | Pitts, Malcolm (Surtek.Inc) | Dean, Elio (Colorado School of Mines)
This study focuses on a multi-well pilot test for a chemical enhanced oil recovery (CEOR) project in Sabriyah Lower Burgan reservoir that is located in the north of Kuwait. The objective of this research is to evaluate the economic applicability of a proposed Alkaline Surfactant Polymer (ASP) formulation based on laboratory core flooding in a multi-well pattern of the candidate reservoir. Simulation and economic modelling was used for this evaluation. Sabriyah Lower Burgan is a large sandstone reservoir with excellent rock properties (Darcy permeabilities). The field is currently developed through primary depletion with an active edge water drive. All forms of EOR were evaluated and CEOR was the only practical technology that passed all screening criteria. Understanding the reservoir behavior is critical and evaluating multiple implementation strategies is important to insure economic success. The objective of the pilot test is to demonstrate that the recommended ASP formulation can economically mobilize remaining oil (ROS) in Sabriyah Lower Burgan reservoir.
North Kuwait has a vision to produce about 1 million BOPD within next couple of year. As a part of this strategy, all efforts & opportunities are being synchronized to maximize the production. A serious threat to this plan was confronted by observation of Naturally occurring radioactive materials (NORM) at some of the producers, a new challenge for which the asset did not anticipate or had any plan earlier. The paper proposal covers how this threat was converted into an opportunity. A comprehensive review of the wells with NORM was done to understand the link to specific reservoir related issues or zone's mineralogy. As this kind of production problem has been faced for the first time in North Kuwait, brainstorming and technical pros & cons were investigated with internal as well as external consultants. A due diligence was conducted to existing rules & procedures within KOC and Kuwait. Case histories from different parts of the world were reviewed as to how such issues had been resolved. Measurement of NORM, accuracy & validity was also looked into, which varied from vendor to vendor. Thus the gathered knowledge was shared with all stake holder teams.
As almost 30-40 MBOPD was the locked in potential, fast track actions have been taken to create a contract to manage wells suffering from NORM. After going through a fast track identification of suitable vendor, contract was awarded to one of the international vendor. Accordingly, workover rigs were made ready to handle NORM remediation operations professionally. Simultaneously, technical evaluation of the performance of wells infected with NORM was done to understand the phenomenon and the relationship with the changes in reservoir pressure / stimulation. A workover schedule was prepared and implemented to revive the shut-in production potential to the GCs, resulting in a bump in oil production for North Kuwait. As a result of the strategy adopted, deferment of oil production due to NORM, which hovered to more than 1.5 years in the past, is prevented, thus helping production target requirements for the Asset. Performance evaluation of wells indicated that there is a strong relationship of reservoir pressure and stimulation with the NORM level.
NORM management requires an integrated team approach, ranging from working units to the organization level and a proactive analytical approach to understand the impact of ongoing sub-surface operations on NORM tendencies. The proper understanding and analysis done in overcoming the NORM has aided in enhancing and sustaining the production via having extended productive life for the wells.