Xu, Wei (CNOOC Research Institute Co., Ltd.) | Chen, Kaiyuan (Beijing Key Laboratory of Unconventional Natural Gas Geological Evalution and Development Engineeing, China University of Geosciences Beijing) | Fang, Lei (Beijing Key Laboratory of Unconventional Natural Gas Geological Evalution and Development Engineeing, China University of Geosciences Beijing) | Zhang, Yingchun (CNOOC Research Institute Co., Ltd.) | Jing, Zhiyi (CNOOC Research Institute Co., Ltd.) | Liu, Jun (CNOOC Research Institute Co., Ltd.) | Zou, Jingyun (CNOOC Research Institute Co., Ltd.)
The lacustrine delta sandbody deposited in the north of Albert Basin is unconsolidated due to the shallow burial depth, which leads to an ultra-high permeability (up to 20 D) with large variation and poor diagenesis. Log derived permeability differs greatly with DST results. Thus, permeability simulation is challenging in 3D geomodeling. A hierarchical geomodeling approach is presented to bridge the gap among the ultra-high permeability log, model and DST results. The ultimate permeability model successfully matched the logging data and DST results into the geological model.
Based on the study of sedimentary microfacies, the new method identifies different discrete rocktypes (DRT) according to the analyis of core, thin section and conventional and special core analysis (e.g., capillary pressure). In this procedure, pore throat radius, flow zone index (FZI) and other parameters are taken into account to identify the DRT. Then, hierarchical modeling approach is utilized in the geomodeling. Firstly, the sedimentary microfacies model is established within the stratigraphic framework. Secondly, the spatial distribution model of DRT is established under the control of sedimentary microfacies. Thirdly, the permeability distribution is simulated according to the different pore-permeability relation functions derived from each DRT. Finally, the permeability model is compared with the logging and testing results.
Winland equation was improved based on the capillary pressure (Pc) data of special core analysis. It is found that the highest correlation between pore throat radius and reservoir properties was reached when mercury injection was 35%. The corresponding formula of R35 is selected to calculate the radius of reservoir pore throat. Reservoirs are divided into four discrete rock types according to parameters such as pore throat radius and flow zone index. Each rock type has its respective lithology, thin section feature and pore-permeability relationship. The ultra-high permeability obtained by DST test reaches up to 20 D, which belongs to the first class (DRT1) quality reservoir. It is located in the center of the delta channel with high degree of sorting and roundness. DRT4 is mainly located in the bank of the channels. It has a much higher shale content and the permeability is generally less than 50 mD. Through three-dimensional geological model, sedimentary facies, rock types and pore-permeability model are coupled hierarchically. Different pore-permeability relationships are given to different DRTs. After reconstructing the permeability model, the simulation results are highly matched with the log and DST test results.
This hierarchical geomodeling approach can effectively solve the simulation problem in the ultra-high permeability reservoir. It realizes a quantitative characterization for the complex reservoir heterogeneity. The method presented can be applied to clastic reservoir. It also plays a significant positive role in carbonate reservoir characterization.
Kuwait Oil Company (KOC) is developing its shallow heavy oil field using thermal method. Top risk of this project is the cap rock failure. If failure occur, it may lead to the steam leakage, overlying aquifer contamination, ground heave or subsidence and surface collapse. For the monitoring ground deformation caused by cyclic steam stimulation (CSS) and steam flooding (SF) thermal operation in Kuwait, InSAR technology is being considered. Interferometric Synthetic Aperture Radar (InSAR) is a remote sensing technique to measure surface heave and subsidence.
First stage of heavy oil thermal development in North Kuwait comprises production from shallow Miocene reservoirs covering an area of roughly 30 square kilometers, by two or three cyclic steam stimulation (CSS) process followed by steam flooding (SF) process. Main reservoirs are the shallow Tertiary un-consolidated sandstone within the measured depth of 650 to 750 feet, sealed off by Up Shale layer that is about 30 FT thick. High pressure and temperature steam will be injected to reservoirs zones, which could result in cap rock breach causing surface heave or subsidence. High-precision and frequent measurements of surface deformation is very important for the study of cap rock integrity.
With the advancement of InSAR technology, millimetric precision of ground deformation measurement is possible. The important factors affecting measurement accuracy of ground deformation is Radar microwave length. The most common of microwave is the L band with 24 cm wavelength, the C band with 4-8 cm wavelength and the X band with 2.5-4 cm wavelength. The choice of wavelength influences the precision. However, there are some other factors which have impact on measurement quality such as spatial density of the measurement points, climatic condition, distance between the measurement points and reference points, number and temporal distribution of acquisitions.
InSAR technology is expected to provide regular surface deformation maps during heavy oil production to monitor the cap rock integrity and to optimize wells and reservoir management. This technology has many benefits, such as reliability, simplicity, low cost, weather independent, minimal field intervention and ability to acquire at night. The absence of vegetation growth in our field area makes this technology very effective. To increase the frequency of data collection and to improve the accuracy of the deformation maps, satellite ascending and descending images are also used. Use of ascending and decending images helps in calculating the vertical and horizontal deformations from the Line of Sight (LOS) measurmemnts.
Al-Murayri, Mohammed Taha (Kuwait Oil Company) | Fadli, Eman Hadad (Kuwait Oil Company) | Al-Shati, Fawziya Mohammad (Kuwait Oil Company) | Qubian, Ali (Kuwait Oil Company) | Li, Zhitao (Ultimate EOR Services LLC) | Trine, Eric (Ultimate EOR Services LLC) | Alizadeh, Amir H. (Ultimate EOR Services LLC) | Delshad, Mojdeh (Ultimate EOR Services LLC)
KOC's Umm Gudair/Abduliyah Tayarat reservoir has large oil reserves but is a challenging target due to low formation permeability and high oil viscosity. This study is focused on feasibility assessment of hybrid thermal and chemical methods incorporating both laboratory and simulation results.
A recent updated static geological model for West Kuwait fields was used as the basis to generate a full-field dynamic reservoir model with representative reservoir geometry, heterogeneity, and complexity. Carter-Tracy aquifers were added to model lateral and bottom aquifers. Laboratory data were incorporated to model physiochemical properties. Gridblocks were globally refined to gain better resolution for heavy oil and EOR simulations. The full-field reservoir model was used to systematically study the potentials of hybrid thermal and chemical EOR methods in comparison with conventional waterflood and chemical EOR methods.
Our studies show that in order to produce oil at an economic rate, long horizontal wells on the order of kilometers or horizontal wells stimulated by acidizing, multistage fracturing, or multiple laterals should be deployed. Vertical wells yield low oil production rates due to limited contact areas and severe water coning. Aquifer water intrusion from the west side of reservoir overshadows the bottom aquifer and the edge east side aquifer due to the heterogeneity of reservoir permeability. A sector model was extracted from the full-field Eclipse model and further refined to avoid grid effects in simulation of EOR processes. Simulation results show that hybrid thermal and chemical methods (hot polymer/Surfactant-Polymer/Alkaline-Surfactant-Polymer flood) can effectively increase oil recovery from high-permeability, high-saturation sweet spots of the Tayarat reservoir. With the help of horizontal wells, hot polymer flood shows the best performance after 20 years of oil production and yields more than 30% of incremental oil recovery. Hot Surfactant-Polymer flood shows slightly lower cumulative oil recovery but sustained oil production rates and less production decline in the late stage of the flood. Phase 2 coreflood experiments confirmed that hot polymer flood can effectively enhance oil recovery.
In summary, this research study identified sweet spots for oil recovery and EOR applications in the challenging Tayarat reservoir and demonstrated the potential of producing significant amount of oil with appropriate IOR (e.g., extended reach horizontal wells, multistage fractures, stimulation, etc.) and EOR (e.g., hybrid thermal and chemical methods) techniques.
Dhote, Prashant Dhote (Kuwait Oil Company) | Al-Bahar, Mohammad (Kuwait Oil Company) | Cole, Anthony (DeGolyer and MacNaughton) | Al-Sane, Amal (Kuwait Oil Company) | Bora, Anup (Kuwait Oil Company) | Sreenivasan, Ashique (Kuwait Oil Company)
Residual Oil Zones (ROZs) are an area of incrasing attention from hydrocarbon E&P industry with ever depleting reserves in known oil accumulations and advent of Carbon Dioxide (CO2) Capture and Storage needs and technology. ROZ can serve as viable solution to both the future problems as a possible vast new oil resource and a prospect for reducing carbon emission. ROZs can be defined as thick pile of low-quality reservoir rock below traditional oil-water contact with about residual oil saturations of mainly irreducible oil resulting from the natural flushing of reservoir due to buoying forces and aquifer action in geological past in earlier oil-filled part of reservoir. The production of oil from ROZs from such reservoirs is technically and economicaly feasible through application of enhanced oil recovery techniques - largely through missible CO2 flooding/injection in the zone because of the nature of fluid and reservoir rock. The depostional and tectonic regime in the Kuwait Petroliferous Basins is investigated to demonstrate the occurrence of and independently assess ROZ potential. The understanding of Kuwait Petroliferous Basin indicates that ROZs might be developed by hydrodynamic actions associated with tectonic regime. The degradation of oil by water action and related increase of sulfur content of crude oil can be used as workable proxy for identification ROZ potential of the rerservoir. The regional mapping, understanding of tectionic history and regional systhesis of crude oil composition shows an extensive stratigraphic and lateral existence of ROZ potential across the Kuwait Petroliferous Basin.
This study aims to provide strategic roadmap and detail data acquisition program that will reveal ROZ production potential in Kuwait for Kuwait Oil Company (KOC).
In this paper we present details of the approach utilized to optimize the well stimulation campaign in the continued development of a huge carbonate gas condensate field in the Offshore Iran. This study discusses what have been done differently, best practices, and learning. What is different in this campaign from previous ones?
Detailed well-by-well review Fundamental data collection for parameters analysis - operational, subsurface, treating fluid data Data management system allowing for quick access Design tool for detailed damage diagnosis, fluid system selection, pumping schedule design, and pressure matches. QA/QC and compatibility tests aiming to obtain high success rate. High contrasts in porosity, permeability and initial pressure Complex mineralogical & lithology composition Fissures and Vuggy porosity Long perforated intervals and well inclination effects Pre-acid nearwellbore reservoir initial condition High rate and ΔT effects on completion & cement integrity Optimum zonal coverage Keep completion integrity while high rate injection Use minimum volume of chemicals Reduce operation risks & costs
Detailed well-by-well review
Fundamental data collection for parameters analysis - operational, subsurface, treating fluid data
Data management system allowing for quick access
Design tool for detailed damage diagnosis, fluid system selection, pumping schedule design, and pressure matches.
QA/QC and compatibility tests aiming to obtain high success rate.
High contrasts in porosity, permeability and initial pressure
Complex mineralogical & lithology composition
Fissures and Vuggy porosity
Long perforated intervals and well inclination effects
Pre-acid nearwellbore reservoir initial condition
High rate and ΔT effects on completion & cement integrity
Optimum zonal coverage
Keep completion integrity while high rate injection
Use minimum volume of chemicals
Reduce operation risks & costs
Optimum acid placement in bullheading treatment in commingled mode is still the challenging issue in in Iran well stimulation jobs. We propose a comprehensive step-by-step workflow to get the best results using Nodal Analysis & Stimulation Software in a logical way described later in the text. Diversion techniques history in this field is: Mechanical diversion, Ball sealers, Selective perforation with polymer based diverter, Selective perforation with high injection rate and VDA technique. Our new diversion method that deployed along with a revised placement model, field calibrated to more accurately predict treatment pressure responses, to optimize acidizing design and to maximize diversion in this layered reservoir, studied in this paper.
Results presented include stimulation treatment plots alongside model post treatment pressure matches, pre and post stimulation production logs, clean up data and well test interpretations to validate the models. We describe high/low permeability, multi zone treatments with a bullheaded matrix acidizing technique. We observed in one well through tubing treatment pressures response and oscillate between 2000 and 3500 psi, far above what is typically observed in this field in which the pressure reduction happened quickly from 3000 to 1000-500 psi.
We conclude that due to enhanced diversion results in uniform zonal depletion which is due to uniform zonal acid coverage. We have also found operational benefits in deploying the system in that commingled zones, normally perforated and stimulated in several stages can now be easily and effectively stimulated using a one-stage technique.
Challenges are usually exaggerated related to matrix acid stimulation and fluid placement in extended reach horizontal wells and demand a constant flow of innovation. The optimization of real time fluid placement, increasing the reservoir contact and establishing uniform fluid distribution for better production/ injection across the openhole interval is one area that can benefit from these new innovations.
Coiled tubing (CT) equipped with a tractor and new real-time downhole flow measurement capabilities was selected as the solution. While a CT tractor facilitates the reach, flow measurements provide a clearer understanding of downhole injectivity patterns. Real-time fluid direction and velocity are acquired and used to identify high/low intake zones. The data is subsequently applied to adjust the stimulation diversion schedule accordingly. In a water injection well, baseline data was acquired before commencing a matrix stimulation treatment. The treatment was squeezed through the CT at the depths highlighted as low intake during the initial profiling.
The coiled tubing real-time flow tool was deployed during the matrix stimulation treatment of the extended reach water injection well with a downhole tractor. The flow tool measured the baseline injection profile which was then correlated with the mobility data. Results from the pre-stimulation profile showed that 70% of injection was entering in a 3,000 ft. section near the toe (24,500 ft.), whereas 30% of injection was spread across the remainder of the open-hole interval. The acquired flow data was able to identify sections of the wellbore featuring low mobility and viscous fluids, which in turn provided additional information for the adjustment of the subsequent stimulation pumping sequence. The real-time optimization of stimulation treatment helped to increase the post-stimulation injection rate by over 4 times the pre-stimulation rate.
The combination of CT tractor with real-time flow measurement tool provides an efficient means to stimulate extended-reach water injector wells. The basic technology behind the real time flow tool is a synchronized system with a series of heating elements and temperature sensors along the tool to determine the direction and mean velocity of the fluid. This ultimately allows for a more accurate placement of stimulation treatment to the targeted zones. The technology can also be applied for extended reach oil producers, however, for optimum tool performance, the well should first be displaced with an inert fluid.
The Burgan reservoir consists of vertically stacked channel sands along with a fault network connected to the aquifer and contains highly viscous reservoir fluid. This dramatically enhances the water mobility and results in severe premature water breakthrough, bypassing zones of oil. This paper describes the use of real-time geochemical analysis to support geosteering of a smart multilateral well located in one of the highest-potential-flow areas of Kuwait. The Minagish field in Kuwait was discovered in 1959 and is located in the southwestern part of the country. It contains several reservoir intervals in its stratigraphic column, varying from Early Jurassic to Late Cretaceous.
Agawani, Waleed (Baker Hughes) | Al-Saffar, Waleed M. (Kuwait Oil Company) | Omar, Marwa (Baker Hughes) | Al-Shehab, Ahmad Y. (Kuwait Oil Company) | Taha, Mohamed (Baker Hughes) | Ahmed, Tausif (Kuwait Oil Company) | Abdelhamid, Atef (Baker Hughes) | Al-Awadhi, Shaimaa (Kuwait Oil Company)
The Umm Gudair 12.25-in. vertical drilling performance section involves several technical challenges for engineering an application-specific PDC bit. The interval consists of two formations that require contradictory bit design principles. The abrasive Zubair formation incorporates sandstones interbedded with hard shale streaks, followed by dual Ratawi intervals of hard shales that are succeeded by compacted limestone. The initial sand interval abrades the cutting structure, resulting in slower rates of penetration in the deeper carbonates. The premature dulling of cutters then causes lower carbonate drilling efficiency. Typically, the section is drilled at 35 feet per hour (fph) and requires 2 bits to complete.
After reviewing offsets with faster than average rates of penetration that successfully completed the interval in the same application, a design compromise was achieved. The new optimized bit design is based on a seven-bladed bit with sixteen-mm cutters. Subsequent design iterations optimized the cutter selection and the cutting structure to maximize durability in the sands while remaining aggressive enough to drill the lower carbonates. An iterative design-and-simulate process then followed, simulating bit stability against formation strength data and optimising drilling fluid flow dynamics. The design was adjusted repeatedly based on the simulation results until a balance in aggressiveness, stability and flow was reached.
After the design process concluded, optimal drilling parameters for each formation were drawn up from offset wells, and the new design was field tested. Drilling stability improved in the sand interval while cutting structure integrity was sustained into the deeper carbonates, resulting in improved rates of penetration in both intervals. After several runs, the results demonstrated that significant gains in rates of penetration were made; reaching over 90 feet per hour (fph) in some cases, almost doubling current rates of penetration. The post-run dull condition of the bits tended to be virtually new (1-1-WT), and in one instance the bit re-ran on a second well, drilling the interval at 53fph.
This paper demonstrates a successful engineering design process for such a challenging section in the Umm Gudair Field. It then highlights the technologies featured in this bit and their value in drilling this application. Finally, field test results are analysed and the improvements in drilling performance and time and monetary savings to the operator are quantified.
Hawie, N. (Beicip-Franlab) | Dubille, M. (Beicip-Franlab) | Guyomar, N. (Beicip-Franlab) | Maury, G. (Beicip-Franlab) | Thomas, V. (Beicip-Franlab) | Vidal, O. (Beicip-Franlab) | Carayon, V. (Beicip-Franlab) | Cuilhe, L. (Beicip-Franlab) | Al-Sahlan, G. (Kuwait Oil Company) | Al-Ali, S. (Kuwait Oil Company) | Al-Khamis, A. (Kuwait Oil Company) | Dawwas Al-Ajmi, M. (Kuwait Oil Company)
Hydrocarbon exploration along the Arabian Peninsula is almost celebrating a century of successes. Major structures were drilled and hundreds of billions of barrels consequently discovered and still producing at increasing rates. Remarkable multi-scale and multi-disciplinary dataset (e.g., 2D, 3D seismic data, core and well log data and imagery…) have been acquired in the past decades allowing geoscientists to better assess the diverse onshore and offshore Petroleum Systems’ potential. Many challenges linked to the exploration of new hydrocarbon resources in such Mature Basins are driving innovative ideas towards the identification, the assessment and the de-risking of new subtle Plays. "Integration" remains a key problematic that needs to be tackled in order to answer properly to how much resources are still left unexplored. Thus, multi-disciplinary expertise, multi-scale dataset combination should be supported by recent technological advances in data acquisition and processing (e.g., 3D Seismic inversion and characterization) as well as by integrated modelling approaches (e.g., 4D Forward Stratigraphic and Basin Modelling).
This paper discusses the results of an innovative methodology developed to assess the exploration potential of the Lower Cretaceous along a wide sector of the mature Eastern Arabian Plate that extends over more than 35 000 km2 (Onshore and Offshore Kuwait).
As major structural features have already been drilled, a focus is set on the detection of subtle stratigraphic trapping mechanisms using multi-disciplinary and multi-scale sedimentological, stratigraphic, petrophysical and geophysical techniques. Seismic stratigraphy study based on reflectors configuration and internal geometry analysis has enabled the delineation of geobodies, i.e. reservoir/seal pairs and proposed conceptual models associated to the presence of subtle traps. A regional
This innovative and integrated workflow applied in mature sectors of the Arabian Plate sets new grounds for the generation of regional Play Fairway Maps, Common Risk Maps for the different Petroleum systems elements (reservoir, seal, trap and charge) as well as Composite Common Risk Maps. These tasks are aimed at assessing the overall risk associated to Plays and thus contribute to the identification of new exploration Lead Areas to be further de-risked in the near future.
Mukherjee, P. (Kuwait Oil Company) | SinghaRay, D. (Kuwait Oil Company) | Golab, A. (FEI Oil & Gas) | Al-Kandari, J. (Kuwait Oil Company) | Quttainah, R. B. (Kuwait Oil Company) | Arena, A. (FEI Oil & Gas) | Mock, A. (FEI Oil & Gas) | Curtis, A. A. (FEI Oil & Gas)
The Najmah and Upper Sargelu formations in Kuwait are tight and unconventional fractured carbonate reservoirs that contain varying amounts of clay minerals and organic matter. Experimental MICP analysis revealed that almost all throats are smaller than 1μm in diameter and most are smaller than 100nm. The pores are poorly connected and this presents challenges for laboratory SCAL experiments. In view of this limitation, the exploitation of the reservoir had been severely constrained for want of parameters critical to reservoir simulation. The contribution of the tight matrix in controlling effective system conductivity needs to be understood to properly simulate production performance (