Ibrahim Mohamed, Mohamed (Colorado School of Mines) | Salah, Mohamed (Khalda Petroleum) | Coskuner, Yakup (Colorado School of Mines) | Ibrahim, Mazher (Apache Corp.) | Pieprzica, Chester (Apache Corp.) | Ozkan, Erdal (Colorado School of Mines)
A fracability model integrating the rock elastic properties, fracture toughness and confining pressure is presented in this paper. Tensile and compressive strength tests are conducted to define the rock-strength. Geomechanical rock properties derived from analysis of full-wave sonic logs and core samples are combined to develop models to verify the brittleness and fracability indices. An improved understanding of the brittleness and fracability indices and reservoir mechanical properties is offered and valuable insight into the optimization of completion and hydraulic fracturing design is provided. The process of screening hydraulic fracturing candidates, selecting desirable hydraulic fracturing intervals, and identifying sweet spots within each prospect reservoir are demonstrated.
The variety and sophistication of upstream technologies have been growing fast for imaging the subsurface, modeling reservoir performance and monitoring oil and gas production. Yet there remains a fundamental need to thoroughly sample and analyze the produced reservoir fluids. Reservoir fluid analysis is critical for understanding the nature of produced hydrocarbons and is the key for production optimization. To gain the maximum value from this analysis, reservoir fluid sampling programs need to be well designed and integrated into well testing and reservoir surveillance programs, and not to be developed after. In one of Chevron's deep-water Gulf of Mexico (DWGOM) sub-salt fields, a robust geochemical sampling plan and production monitoring program has been in place since initial production to estimate the zonal contribution from individually stacked reservoirs. This surveillance work has been ongoing for 9 commingled wells over a period of 10 years.
Abdel Mageed, Mohamed (Khalda Petroleum Company) | Awad, Mostafa (Khalda Petroleum Company) | Hussein, Ahmed (Khalda Petroleum Company) | Osman, Ahmed (Schlumberger) | Siam, Mahmoud (Schlumberger) | Al-Kaabi, Mohammed (Schlumberger) | Rafik, Ahmed (Schlumberger)
Egypt's Western Desert is known to be a highly complex and difficult drilling environment. Drilling in this area suffers from multiple geological risks related to formation dip and hardness, faulting, interbedding, and abrasive lithology. These conditions have typically caused drilling problems and costly delays in wells delivery. Combined with the geological difficulties, differences in the implemented drilling practices and operational procedures have led to inefficiencies and the loss of some knowledge transfer among different drilling activities and field operations.
For a proof of concept in one of its fields, Khalda endorsed a drilling automation and operations benchmarking strategy to improve the well delivery time in one of its Western Desert fields. The strategy focused on on-bottom drilling activity as well as off-bottom practices and flat-time activities. One part of this strategy endorsed a real-time automated drilling optimization workflow for the on-bottom drilling activities whereby the implementation of a change-point algorithm dictates the optimum drilling parameters to obtain the best possible rate of penetration (ROP) within the rig and drilling assembly constraints and while operating within the safe drilling dynamics window for the assembly. This approach yields the optimum ROP and prevents any possible downhole equipment failure or premature bit damage. The other part of the strategy involved benchmarking the different rig activities while drilling or doing other mechanical operations to gauge the activity of the current well compared to the offset well. This highlights any inefficiencies that can be immediately overcome, areas of improvement, and key learnings for future optimization or implementation.
This strategy was implemented in a deep gas development well in a challenging Western Desert field with known problematic offsets. The results showed a step change in well delivery whereby the well finished 3 days ahead of plan and 7 days ahead of the offset well. The real-time automation technique for drilling optimization managed to show 24% on-bottom ROP improvement in one section, enabled completing another section with a one run less than offset, and managed to mitigate the harsh drilling dynamics to prevent downhole equipment incidents. Also, the activities benchmarking helped to develop standard drilling practices that reduced inefficiencies in off-bottom drilling activities by 50% and managed to highlight key learnings and areas of development for future wells. These results helped in validating the proof of concept set at the beginning of this pilot.
Kholy, S. M. (Advantek Waste Management Services) | Sameh, O. (Advantek Waste Management Services) | Mounir, N. (Advantek Waste Management Services) | Shams, M. (Advantek Waste Management Services) | Mohamed, I. M. (Advantek Waste Management Services) | Abou-Sayed, A. (Advantek Waste Management Services) | Abou-Sayed, O. (Advantek Waste Management Services)
Oilfields produce huge amount of waste on daily basis such as drilling mud, tank bottoms, completion fluids, well treatment chemicals, dirty water and produced saltwater. These waste types represent a real challenge to the surrounding environment especially when the oilfield is located within a sensitive environment as in the Western Desert where there are natural reserves and fresh water aquifers. Waste slurry injection has proven to be an economic, environmentally friendly technique to achieve zero waste discharge on the surface over the past years. This technique involves creating a hydraulic fracture in a deep, subsurface, non-hydrocarbon bearing formation which acts as a storage domain to the injected slurrified waste. The objective of this study is to evaluate the feasibility of waste slurry injection in an oil prospect located in the Western Desert. The evaluation includes assessing the subsurface geology, recognizing the possible candidate injection formation(s), and designing the optimum injection parameters.
Both geological and petrophysical data have been used to create the geomechanical earth model for an oil prospect located at Farafra oasis in the Western Desert. This model defines the mechanical properties, pore pressure, and in-situ stresses of the different subsurface formations. Afterwards, a fully 3D fracture simulator has been used to simulate the fracture growth within the candidate injection zone at different injection scenarios. Additionally, the fracture simulator has assessed the containment of the created fracture within the candidate injection formation(s) due to the presence of stress barriers above and below the formation. Finally, the formation disposal capacity has been calculated for each of the injection scenarios using a stress increment model.
The geomechanical earth model shows that there is a good candidate injection zone which is upper/lower bounded by stress barriers. More importantly, it is located deeper than the local fresh water aquifer and thus no contamination is expected to the fresh ground water. In addition, the possible candidate is not a hydrocarbon bearing formation.
A 3D fracture simulator has been used to determine the optimum injection parameters such as: the injection flow rate, the volumetric solids concentration, the slurry rheology and the injection batch duration. These optimum parameters are defined to minimize the stress increment rate over the well life, which ensure the highest disposal capacity and to contain the fracture within the candidate injection formation.
Guidelines to conduct waste slurry injection technique in a new oil prospect that is located within a sensitive environment as in the Western desert are presented in this study. Also, the study highlights that this technique is economic for disposal of the different oilfield waste types in an environmentally friendly fashion.
Standard Rock-Eval pyrolysis is commonly used to estimate the thermal maturity of source rocks. However, measuring the maturity of overmature samples with high Tmax values (> 470°C) is very challenging due to the weak development of S2 peaks. Moreover, measuring the vitrinite reflectance of dispersed organic matter high thermal maturity samples is commonly used when the Tmax (°C) of the sample is unreliable. Nevertheless, vitrinite assemblages are very rare/absent in marine samples particularly in marlstones or pre-Carboniferous source rocks. The current study addresses a new thermal maturity parameter that used the carbon monoxide CO released during Rock Eval-6 oxidations.
A total of 14 marine source rock samples were analyzed by Rock Eval-6 to assess their generative potential. The samples range in Tmax from 420° to 475°C indicating wide thermal maturity range from immature to overmature. During Rock-Eval analyses, CO released from the kerogens and their peak temperature (Tco) was recorded. A strong positive correlation was observed between the Tmax and the Tco (r=0.94). Note that the CO is released from the organic oxygen compounds that are none/or less liable compared to pure hydrocarbon compounds. Thus, Tco is more reliable than Tmax in assessing high thermal maturity levels.
The new method provides a robust and quick interpretation of high thermal maturity source rocks especially for pre-Carboniferous samples that lack a well-devolved S2 peak. Carbon monoxide generation is not affected by carbonate decay to CO2 and is also not affected by contamination used in drilling fluids. Testing of different source rocks is needed to establish this further and to improve the trend observed.
Nuclear magnetic resonance (NMR) T2 spin-spin relaxation is a well-established technique in petrophysics labs for quantifying bound/free water and pore-size distribution of reservoir rocks. The method has also been used to measure oil and water saturations, and to characterize wettability alterations for oil/water/rock systems. The T2 relaxation distribution measured by hydrogen NMR is the sum of contributions from both oil and water in the core. It is therefore necessary to separate the T2 signals of oil from water. Since deuterium oxide (D2O) does not have a NMR signal at the resonance frequency for hydrogen, brine made with D2O is commonly used as the aqueous phase to determine the oil saturation from NMR.
The objective of this work was twofold: (1) to validate the oil saturations in the core with NMR T2 relaxation at connate water saturation (before and after aging) and residual oil saturation after waterflooding; and (2) to investigate the potential hydrogen-deuterium (H-D) ion exchange between rock minerals and D2O. Berea sandstone cores were used along with the crude oil from one of the fields in the Sarawak Basin, Malaysia. The aqueous phase was a synthetic brine made with either deionized water or D2O.
Two cores containing the crude oil with D2O brine as the connate (or initial) water were aged at 75eC for up to 65 days. During the aging period, the cores were scanned three times for T2 measurements. The measured T2 volumes (supposedly a measure of the oil volume) of the two cores kept increasing as the aging time increased. However, mass balance indicated that the oil saturation was the same before and after aging. The inconsistent oil saturation measured by NMR indicated that there was H-D ion exchange between the rock minerals and D2O. The cores were then flooded with the fresh D2O brine, after which the residual oil from NMR agreed with that from mass balance, indicating that the fresh D2O had replaced the connate D2O brine affected by H-D ion exchange.
Additionally, two cores fully saturated with D2O brine were also measured by NMR before and after aging at 75°C, again confirming the H-D ion exchange between the rock minerals and D2O. Finally, the mixture of the crude oil and D2O was measured by NMR before and after aging at 75°C, indicating that the interactions between the crude oil and D2O increased the T2 relaxation time. The total T2 volume was not affected.
This work provides evidence of H-D ion exchange between rock minerals and D2O at elevated temperature. It is recommended that such interactions between the rock minerals and D2O brine be considered for related tests, especially when elevated temperature is involved.
This seminar covers the fundamental principles concerning how hydraulic fracturing treatments can be used to stimulate oil and gas wells. It includes discussions on how to select wells for stimulation, what controls fracture propagation, fracture width, etc., how to develop data sets, and how to calculate fracture dimensions. The seminar also covers information concerning fracturing fluids, propping agents, and how to design and pump successful fracturing treatments. As the industry wrestles with another price cycle, making sense of the world in which the oil and gas industry will operate is important to understanding the actions (by engineers, corporations, and governments) which must be taken today so that the oil and gas industry may prosper in the future. Hydraulic fracturing has been touted as a ‘new technology’ (though a misnomer) which is opening access to un-tapped value (in the USA) and lowering the cost of energy across the globe by shifting the balance between supply and demand.
The Apollonia tight-gas chalk play is located in the Abu Gharadig Basin in the Western Desert of Egypt. This has long been ignored as a gas play in the overburden, while the Jurassic and Cretaceous oil fields deeper in the basin have been explored and developed. Large areas of the North Sea contain Cretaceous sediments, which form a massive hard layer of chalk that historically has presented a major drilling risk and expense to operators in the area.
The benchmark comes as operator Eni solidifies concession agreements and ramps up exploration and development in the North African country. The Apollonia tight-gas chalk play is located in the Abu Gharadig Basin in the Western Desert of Egypt. This has long been ignored as a gas play in the overburden, while the Jurassic and Cretaceous oil fields deeper in the basin have been explored and developed. More gas is flowing from Egyptian waters and the Eastern Mediterranean with BP’s launch of its Atoll Phase One project. Partnerships are proving key in developing and sustaining big offshore projects internationally, with Eni now teaming with ADNOC off Abu Dhabi and farming out another stake in the Zohr gas field off Egypt.
The Apollonia tight-gas chalk play is located in the Abu Gharadig Basin in the Western Desert of Egypt. This has long been ignored as a gas play in the overburden, while the Jurassic and Cretaceous oil fields deeper in the basin have been explored and developed. Dubai Petroleum embarked on a new mission last year to drill and complete its first multistage, hydraulically fractured, and propped horizontal well from an offshore platform. This paper gives the recommended MSF horizontal-well spacing for several development scenarios in Saudi Arabian gas-reservoir environments. A tight gas carbonate reservoir with no oil rim in a supergiant onshore gas field in Abu Dhabi was targeted for stimulation during a field review to increase field production.