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Results
Analysis of the Sources of Uncertainty in Geopressure Estimation While Drilling
Cayeux, E. (NORCE Norwegian Research Center, Stavanger, Norway) | Daireaux, B. (NORCE Norwegian Research Center, Stavanger, Norway) | Macpherson, J. (Baker Hughes, Houston, USA) | Bolt, H. (Depth Solutions, London, UK) | Harbidge, P. (Expro, Kuala Lumpur, Malaysia) | Annaiyappa, P. (Nabors, Houston, USA) | Carney, J. (NOV, Stavanger, Norway) | Ziadat, W. (Weatherford, Dhahran, Saudi Arabia) | Edwards, M. (Edwards Energy Innovation Consulting, Houston, USA)
Abstract Geopressure estimation is an important aspect of well planning and execution. However, there are many sources of uncertainty that can affect the accuracy and timing of the prognosis. These uncertainties are associated with data produced by many different disciplines at various times throughout the life of the well. As subject matter experts tend to work in silos these uncertainties are often unshared, and there is no appropriate routine performance of uncertainty propagation across disciplines. This can negatively affect decision making during both the engineering and operational phases of a well. Uncertainty requirements across disciplines are often not formulated into coherent uncertainty management. It is therefore important to understand the possible sources of uncertainty to better quantify the estimation of geopressures and to make smarter decisions. This paper describes the uncertainties associated with each estimate of geopressure, their locations in the multi-discipline silos, and the current relationship between estimates. With this comes the realization of a structure or method for combining the individual uncertainties to provide a clearer idea of geopressure estimation and its inherent uncertainty. For instance, combining wellbore position uncertainty with the stratigraphic earth model uncertainty makes possible the estimation of the spatial probability distribution of particular geopressure related observations. The sources of information for geopressure prognosis are many, spread across disparate systems with various discipline ownership. Even direct and real-time observations of formation fluid influx, borehole collapse or formation fracturing can depend on the precision of downhole pressure measurements and knowledge. Extrapolate measured downhole pressures to positions far removed from the measurement point is often necessary. This requires accurate calculation of hydrostatic and hydrodynamic pressures and the wellbore and vertical depth positions to infer pressure profiles along the borehole. These profiles are a function of the accuracy of characterization of the pressure and temperature behavior of the drilling fluid properties and the well depth. Temperature estimations depend on definition of geothermal gradients and the precision of heat transfer calculations causing a varying degree of accuracy for baseline profiles to base operational decision. It is possible to measure pore pressures in situ, or to estimate them using trend analysis of formation evaluation or drilling logs. Factors influencing the precision of the results include the actual measurement depth value uncertainty, and the impact of wellbore position uncertainty on their correlation with an earth model. Leak-off tests deliver information about geopressure margins, but the interpretation of flow-back measurements creates further uncertainties that propagate across the prognosis. The propagated uncertainties from all these sources can be derived using stochastic simulations, yielding, when combined, a quantitative assessment of geopressures. In addition, Kriging methods can incorporate new geopressure estimations in a geomechanics oriented earth model. The paper provides a list of possible sources of uncertainties and a possible categorization of their origins. It describes the causal links between the sources of uncertainties and their effect on the quality of geopressure prognosis. The purpose is to facilitate the adoption of quantitative uncertainty assessment methods by the well construction community for geopressure estimations.
- Europe > Norway (0.68)
- North America > United States > Texas (0.46)
- Geology > Geological Subdiscipline > Stratigraphy (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geophysics > Seismic Surveying (1.00)
- Geophysics > Borehole Geophysics (1.00)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Drilling > Well Planning > Trajectory design (1.00)
- Well Drilling > Pressure Management > Well control (1.00)
- (13 more...)
- Information Technology > Data Science (1.00)
- Information Technology > Architecture > Real Time Systems (0.66)
- Information Technology > Artificial Intelligence > Representation & Reasoning > Information Fusion (0.46)
- Information Technology > Artificial Intelligence > Machine Learning > Statistical Learning (0.46)
Abstract The objective of this paper is to discuss shale-fluid interactions while drilling clay-rich shale formations. Shale swelling, dispersion and sloughing are frequently encountered problems that may lead to excessive non-productive time. Comprehensive understanding of the behavior of the shale sample helps in mitigating shale drilling problems. To understand the behavior of a shale sample when exposed to fluids, different types of characterization tests have been conducted starting with mineralogy identification using X-ray diffraction, X-ray fluorescence and also the conventional swelling tests. It went further to study the organic carbon content using thermogravimetric analysis. After carrying out X-ray diffraction and thermogravimetric analyses on two shale samples to determine clay content and organic carbon content, a series of swelling tests were conducted using different types of non-inhibitive and inhibitive fluids. Linear shale swelling results are represented as the percentage of volume expansion as a function of swelling time while shale. Results showed high variance among shale inhibitors in terms of the ability to inhibit shale particles for prolonged time intervals This paper provides a review of various factors that influence shale-drilling fluid interactions Due to the presence of some unique conditions, such as loss circulation, sometimes there is a need to use a low cost non-inhibitive mud instead of a high cost inhibitive mud to drill the next formation after the shale section. If the durability of original inhibition is not long enough to ensure smooth drilling of the the second zone, the previously drilled inhibited shale formation starts reacting again with the non-inhibitive drilling fluid. Hence, the reactive shale zone needs to be isolated by a casing string before drilling ahead. However, if inhibitive muds with long-term inhibition potential such as 24 hours or more are available, multiple formations including the shale formation can be drilled and cased in one hole section.
- North America > United States > Texas (0.28)
- Asia > Middle East > Saudi Arabia (0.28)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid management & disposal (1.00)
- (2 more...)
Abstract Hydraulic fracturing experiences were gathered over the years, from a tight sandstone reservoir of Late Carboniferous to Early Permian origin to find the root causes for the persisting challenges of high formation breakdown pressures and low fluid injectivity. It was soon realized that a single root cause could not account for these challenges. Instead, a multitude of reasons acting at the same time during the injecting sequence of that particular fracturing stage could easily be responsible, and no single re-occurring pattern would explicitly repeat in the consequent stages under similar conditions. It was found that the known complex nature of the depositional environment of the targeted formation played an important role, but the overall hydraulic fracturing mechanics played an equally critical part in the success of the fracturing attempt. Having realized this complexity in deciphering hydraulic fracturing performances it became imminent that not only the fracturing execution had to be refined, but all the preceding activities from drilling operations, to well placement, to wellbore preparation, to the choice of completion equipment and its deployment. These operations critically influenced the near wellbore region. The drilling fluid properties, wellbore hydraulics, well trajectory, the wellbore clean-out procedures, and hole quality were important contributors in the geo-mechanics domain coupled with the impact of the geological setting. Thus, a workflow was developed to analyze and rationalize the root causes for the injectivity challenges with the goal of optimizing every well construction step that would enhance hydraulic fracturing and ultimately deliver optimum well productivity.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.54)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Drilling > Drilling Operations > Directional drilling (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (1.00)
- (6 more...)
Abstract Metal Oxide Nanoparticles (MONPs) comparison has been used for the first time as Nanoshale inhibitors in water-Based Drilling Fluids. These Nanoshale inhibitors used in this study eliminate the use of toxic high potassium chloride (KCl) concentration in shale drilling operations and environmentally friendly with reducing the cost of drilling fluid treatment and waste disposal. The dispersion test of Nanoshale inhibitors based on MONPs with shale samples revealed to be an effective candidate with significant interaction reduction between the drilling fluids and the shale particles compared without these Nanoshale inhibitors samples. This new Nanoshale inhibitor maintains the integrity of the cuttings and minimize the interaction of fluids with shale sections during the rolling test. Zeta potential (ZP) has been conducted to determine the charge of shale and nanoparticles samples. Although the application of nanoparticles to improve the performance of conventional water-based drilling fluid was studied by researchers, it is the novelty of this research to eliminate use of KCl and to develop the new generation of Nanoshale water-based drilling fluid with economical consideration and lower environmental impact.
- North America > United States > Texas (0.94)
- Asia > Middle East (0.94)
- Europe (0.68)
- North America > United States > Texas > Fort Worth Basin > Barnett Shale Formation (0.99)
- North America > United States > New Mexico > Permian Basin > Atoka Field > San Andreas Formation (0.98)
- North America > United States > West Virginia > Appalachian Basin > Marcellus Field > Marcellus Shale Formation (0.89)
- (7 more...)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid management & disposal (1.00)
- (4 more...)
Innovative Solutions to Subsurface Challenges in Deep Hard Rock High Temperature Slim Wells
Wahshi, Khalifa Omair (Petroleum Development Oman) | Thomas, Boris Jean (Petroleum Development Oman) | Khaldi, Saud Ali (Petroleum Development Oman) | Haji, Younis Said (Petroleum Development Oman) | Salehi, Yasir Mohammed (Petroleum Development Oman) | Yuan, Roger Shihche (Petroleum Development Oman) | Mahrooqi, Ali Khalfan (Petroleum Development Oman) | Harthy, Khalid Nasser (Petroleum Development Oman) | Habsi, Fahad Said (Petroleum Development Oman)
Abstract In this paper we present the challenges faced in one of PDO's onshore a deep (5200 mTVD) field. Among these challenges were hardness of the rocks, 40 ksi and a high temperature of 155ºC. Further, well bore instability, tectonic stresses and depletion. The time consumed to overcome these subsurface challenges with conventional drilling methods was affecting the economic attractiveness of some of the wells. A multi-disciplinary taskforce was established with the remit to improve overall well economics by overcoming field challenges and by turning some of the challenges into opportunities. The working group identified opportunities across several themes that were deemed to have the highest impact on the well economics, well design and materials selections and new technologies. The introduction of a new design concept of (Fast Degradation Brine) in the annulus allowed a reduction of the brine weight after cementing the completion. This change enabled passing specific casing design burst loads associated with the reduction of the 7" liner weight from 35 to 29 ppf. This allowed drilling larger hole sizes of 6" and 6 1/8" instead of 5 7/8". H2S fugacity concept was used instead of the conventional partial pressure concept to evaluate the sour severity of the materials. In new technologies, Motorised Reamer Shoe (MSR) drive system, was piloted for the first time in PDO's cemented completion to enable re-drilling and reaming ledges and hole closure caused by tectonic stresses during the completion run. A Polymer Borate System (PBS) plug has proven to be an effective new technology, used as lost circulation material for dealing with severe losses in PDO. Through introduction of new well design concepts, new technologies and new ways of working we managed to: - Safeguard reserves and enable full access to target reservoirs by overcoming drilling challenges through improvements in the well design. - Realise a 40%-well delivery time reduction, coupled with a significant reduction in NPT. - 30%-reduction in average well cost. - Realise cost saving of 2.9% through well design optimisations. We managed to safeguard production which would be lost in case of short landing the completion. - Replicate MSR technology on planned side-tracks in PDO's wells, and we are planning to apply this technology in horizontal wells. The technology will also be an enabler to further slim down well designs in other fields. - Put in place a replication plan for applying the H2S fugacity concept wherever applicable. The well design concepts and new technologies mentioned above are novel or new to PDO.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Structural Geology > Tectonics > Plate Tectonics > Earthquake (0.45)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.30)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Drilling > Well Planning (1.00)
- Well Drilling > Pressure Management > Well control (1.00)
- (5 more...)
Abstract Environmentally friendly Mesoporous Silica Nanoparticles (MSNs) has been used for the first time as a Nanoshale inhibitors in water-Based Drilling Fluids. Nanoshale inhibitors used in this study eliminate the use of toxic high potassium chloride (KCl) concentration in shale drilling operations and reduce the waste management associated cost with drilling fluid treatment and disposal. The dispersion test of MCM41 Nanoshale inhibitor with Silurian shale samples revealed to be an effective candidate with significant interaction reduction between the drilling fluids and the shale particles. This new Nanoshale inhibitor maintains the integrity of the cuttings and minimize the interaction of fluids with shale sections during the rolling test. XRD patterns has been conducted to determine the crystalline structure of shale and nanomaterial samples. Although the application of nanomaterials to improve the performance of conventional water-based drilling fluid was studied by researchers, it is the novelty of this research to eliminate use of KCl and to develop the new generation of Nanoshale water-based drilling fluid with economical consideration and lower environmental impact.
- North America > United States > Texas (0.46)
- Asia > Middle East > Saudi Arabia (0.28)
- North America > United States > Texas > Fort Worth Basin > Barnett Shale Formation (0.99)
- North America > United States > West Virginia > Appalachian Basin > Marcellus Field > Marcellus Shale Formation (0.89)
- North America > United States > Virginia > Appalachian Basin > Marcellus Field > Marcellus Shale Formation (0.89)
- (6 more...)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- (4 more...)
Abstract The effect of kaolinite fine particles migration and wettability alteration during low salinity water-flooding (LSW-flooding) has been investigated for Omani sandstone reservoirs. Water flooding by re-injecting the reservoir brine is currently operated in the subjected Omani oil fields, and LSW is one of the operations to improve the oil production. However, relatively large amount of precipitated oil sludge was observed in the production and surface facilities along with the produced crude oil. In present experimental study, Omani intermediate oil (API gravity of 30°) and oil sludge were sampled from a skimming tank in the production facility. The physical and chemical characteristics of the clay particles were analyzed by a laser particle size distribution analyzer, SEM, XRD, and SQX after separated from oil. Furthermore, water-flooding tests by brine and LSW were carried out using Berea sandstone cores saturated by three different conditions of the Omani oil and kaolinite fine particles to simulate clay particles in the reservoir conditions. The kaolinite-particles slurry of 0.4μm in average size were used for the tests. The first core was saturated with oil only, the second one was filled up with kaolinite fine particles slurry then saturated with the oil, and the third one was saturated with the mixture of kaolinite-particles slurry and the oil. The results of LSW flooding after brine flooding showed that 30 % increase of oil recovery was obtained in the cases including kaolinite fine particles compared to that of oil only. In addition, the wettability of the cores contained kaolinite fine particles showed stronger water-wettability than the core without kaolinite. Zeta potential was measured to investigate the surface charge of kaolinite-particles in brine and water. The kaolinite fine particles were negatively charged as -15 mV in the brine, while it was -50 mV in the LSW used for the LSW flooding test. This difference has explained that the increase of oil recovery ratio in the water-flooding test was induced by kaolinite fine particles in the cores. The ions were traced in the effluents in LSW flooding, and it was found that the concentration of Ca2+ and Mg2+ reduced sharply from their initial concentration of 722 and 788 ppm to 34 and 26 ppm respectively with pH increasing from 6.8 to below 9.0.Those results indicate clearly that the kaolinite fine particles have a function to reduce the Sor and shift the wettability to water-wet that attributed to the interactions between oil, water and kaolinite-particles in the process of LSW flooding.
- Asia > Middle East > Oman (0.46)
- North America > United States > California (0.28)
- North America > United States > Texas (0.28)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (1.00)
- Geology > Mineral > Silicate > Phyllosilicate (1.00)
- Europe > Russia > Volga Federal District > Tatarstan > Volga Urals Basin > Pervomaiskoye Field (0.99)
- Europe > Norway > North Sea > Northern North Sea > East Shetland Basin > PL 375 > Block 34/7 > Snorre Field > Statfjord Group (0.99)
- Europe > Norway > North Sea > Northern North Sea > East Shetland Basin > PL 375 > Block 34/7 > Snorre Field > Lunde Formation (0.99)
- (10 more...)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid management & disposal (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
Abstract In the Permian basin, Spraberry Trend is one of the formations that markedly contribute to the unconventional shale production in the U.S. lately. Unusual shale reactivity was encountered while drilling several horizontal wells, leading to wellbore instability issues. Consequently, shakers’ screens blockage increased the mud losses and drilling time, leading to an increased non-productive time (NPT). This paper addresses the challenges and causes of the formation instability issues resulted from shale interaction with the used drilling fluid and presents the timely actions taken to mitigate such problems. During the drilling operation, several rock samples were collected at different depth intervals from the shale shaker. Rock samples were analyzed to identify the clay and minerals contents in the formations. The collected samples were first cleaned to remove the mud, dried, ground, and then characterized by an X-ray diffraction test (XRD) and microscopic imaging. After identifying the possible reasons for the wellbore instability, several timely actions were taken to mitigate this issue. These actions include: 1) increasing the emulsion stability, 2) increasing the water phase salinity (WPS), 3) decreasing the water phase volume, 4) adding wetting agent, 5) using wider screens for the shaker, and 6) controlling drilling parameters such as weight on bit and rotational speed. Afterward, wellbore stability, well control problem indicators, and drilling fluid properties, especially rheology, were closely monitored to identify any subsequent or unusual events. The geological and mineralogy studies show that the drilled formation contains high smectite and illite clay content, up to 49%, which was believed to be the main reason for the unusual shale reactivity. Replacing the existing screens (200 API) with wider screens (160 and 140 API) showed an insignificant effect in mitigating the screens blockage. The adopted method of reducing the rate of penetration (ROP) and increasing the circulation time helped significantly alleviate the screens blockage by reducing the cuttings production and giving more time for hole cleaning. Furthermore, the optimal hole cleaning successfully increased the formation's stability. Adding a wetting agent to the drilling mud did not impact the cuttings aggregations; however, it led to a decrease in the rheological properties; thus, adding more concentration of the viscosifier was required to maintain the fluid rheology. Increasing the water phase salinity (WPS) to over 230k ppm and the emulsion stability to over 700 mV was considered the backbone of the treatment plan that significantly resolved the issue by inhibiting the clay. Eventually, the critical considerations were pointed out.
- North America > United States > Texas > Midland County (0.24)
- North America > United States > Texas > Martin County (0.24)
- North America > United States > Texas > Howard County (0.24)
- North America > United States > Texas > Dawson County (0.24)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Mineral > Silicate > Phyllosilicate (1.00)
- Geology > Geological Subdiscipline (1.00)
- North America > United States > Texas > Permian Basin > Yeso Formation (0.99)
- North America > United States > Texas > Permian Basin > Yates Formation (0.99)
- North America > United States > Texas > Permian Basin > Wolfcamp Formation (0.99)
- (27 more...)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Drilling > Drilling Operations (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (1.00)
- (2 more...)
High-Performance-Low-Invasion Fluids Technology Enhances, Optimizes Drilling Efficiency in the Gulf of Suez - Egypt
Mohamed, Youssry Abd El-Aziz (Egyptian Mud Engineering and Chemicals Company) | Kheir, Mahmoud Mohamed (Egyptian Mud Engineering and Chemicals Company) | Al-Zahry, Ayman Abd El-ghany (Egyptian Mud Engineering and Chemicals Company) | Salama, Ayman Salama (Gupco / Dragon Oil Limited) | Ouda, Abdalla Ahmed (Gulf of Suez Petroleum Co.) | Abou El Maati, Lotfi Ibrahim (Gupco / Dragon Oil Limited) | Ahmed, Mohamed Farouk (Gupco / Dragon Oil Limited) | Mohamed, Sally Ahmed (Gulf of Suez Petroleum Co.)
High Performance Low-Invasion Fluids Technology Enhances, Optimizes Drilling Efficiency in the Gulf of Suez – Egypt Objectives / Scope: The main objective of this paper is to characterize the drilled shale formation in order to select and propose a "tailored" High Performance Low Invasion Fluids (HPLIF) system aided by Bridging Particles Optimization Tool (BPOT), capable of maximize hole stability in pressure depleted sands, allowing optimized well design through reactive and dispersible shale formations that eliminated one casing section, and to replace Oil Base Mud (OBM) and avoid its HSE issues related to use it, consequently, reduce formation damage, eliminate waste management cost, minimizing Non Productive Time (NPT) and finally enhances Drilling performance. Methods, Procedures, Process: This paper explain the reactivity information about Shale Samples recovered from different wells drilled in the-GOS-Egypt followed by extensive laboratory testing done in order to characterize the main clay minerals presented in the samples using X-Ray Diffraction-(XRD) technology and their meso-and micro-structure by Scanning-Electron-Microscope-(SEM) and their reactivity to compare the inhibition efficiency of the proposed-(HPLIF)-System with Blank and Conventional Water-Base-Fluid-System. The reactivity of the cuttings was assessed by Dispersion, Swelling and Hardness tests. Field application experienced (HPLIF) System combined with Well-Bore Strengthening Materials (WSM) gives the required protection against induced losses and reducing the risk of differential sticking problems when mud overbalance is above 2500 psi. Results, Observations, Conclusions: Compared with the use of conventional fluid systems, Field data demonstrated the successful application of (HPLIF) System combined with (WSM) and shows a great success during drilling through reactive clays, dispersive shale, naturally micro fractured, and depleted sand formations in many wells drilled in the GOS. Drilling operations reported no differential sticking, or wellbore instability issues even at highly mud overbalance or at highly deviated wells. The first challenged well R1-63 was drilled about 2391 ft, through 8.5" hole using 9.8-10.01 ppg using (HPLIF) system, penetrating through Thebes, Esna Shale, Sudr, Brown Lime Stone, Matulla, Nubia"A" Sand and Nubia "B" without any down-hole losses. Additionally, there was no sticking tendency experienced during drilling or while recording pressure points. The Non Productive Time NPT showed a reduction by about 19.2%. Finally, it ran and was cemented the "7" Liner in open hole successfully without problem. For the second challenged case well # 2, the Open hole was exposed to (HPLIF) water based mud system for a long period of time while rig repairing, rig switching, and during drilling operation. The well had 6" hole from 12,752 To/14,945 (2193.0ft) through Red bed, Thebes Esna, Sudr, Matulla and Nubia Sand formations with max inclination 68.6° and bottom hole temperature 325°F using 10.0-10.5 ppg (HPLIF) system, the 4.5"liner successfully was ran, cemented without any problems. The-HPLIF-System has also been shown to give excellent wellbore stability in brittle shales Fm where bedding planes or micro-fractures can become pressurized with mud, leading to wellbore instability. This innovation avoids induced lost circulation and differential sticking when the mud overbalance is expected to be greater than ±2500 psi. Additionally, the proposed solution enhances the drilling operation, reduces the waste management costs, eliminates a possible additional casing string, and finally minimizes the (NPT) which reflects on the overall cost of drilling these challenged wells.
- Africa > Middle East > Egypt > Gulf of Suez (0.93)
- Africa > Middle East > Egypt > Suez Governorate > Suez (0.60)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Mineral (1.00)
- Africa > Middle East > Egypt > Gulf of Suez > Gulf of Suez Basin > Ramadan Field (0.99)
- Africa > Middle East > Egypt > Gulf of Suez > Gulf of Suez Basin > Kareem Formation > Shagar Member (0.98)
- Africa > Middle East > Egypt > Gulf of Suez > Gulf of Suez Basin > Nubia Formation (0.96)
- Africa > Middle East > Egypt > South Sinai Governorate > Lagia Field > Nukhul Formation (0.94)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Drilling > Drilling Operations > Drilling optimization (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (1.00)
- (2 more...)
Abstract To minimize the formation damage that drilling induced, CNOOC has launched oil-based mud (OBM) drilling campaign since 2019 in Xihu sag in East China Sea to create more user-friendly environment for acquisition of better data quality for formation evaluation. However, OBM system has its own challenges in their reservoirs: (1) Hydrocarbon from multiple source rocks was charged into the system, condensate and volatile oil distribution undergo the complex fluid system cross reservoir; (2) Both faults and lithology are interacted to control reservoir trap, which makes the fluid distribution complex; (3) Though oil-based mud system can protect formation from damage more effectively compared with water-based mud, its contamination to reservoir fluid presents a strong challenge to fluid types and fluid phase envelope changes. Downhole Fluid Analyzer (DFA) isn’t a new technology in the industry, and its OBM contamination monitor is well known method published by many authors. In this paper, we presented a comprehensive case study of 6 wells in Xihu sag and implemented quantifying OBM contamination real-time, to understand the fluid distribution across the reservoir integrating with PVT analysis in this faulted geological structure. On the other hand, the formation mobility and OBM contamination relationship was studied to understand the impact of formation property on the sample quality, so it provided the operation suggestion for the future exploration to improve the data acquisition and reduce fluid measurement uncertainty further for reservoir characterization.
- Asia > China (1.00)
- North America > United States > Texas (0.47)
- Geology > Rock Type (0.87)
- Geology > Structural Geology > Fault (0.68)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (0.34)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > Asia Government > China Government (0.35)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid selection and formulation (chemistry, properties) (1.00)
- Well Drilling > Drilling Fluids and Materials > Drilling fluid management & disposal (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- (4 more...)