Gouda, G. (Eni Egypt) | Kaja, M. (Eni Egypt) | Abdel Fattah, S. (Petrobel) | Shaker, E. (Petrobel) | Abd ElHakim, W. (Petrobel) | Korany, M. (Petrobel) | Samir, E. (Schlumberger) | Metwally, A. (Schlumberger)
Abu Rudeis Field is considered one of the oldest oil fields in the Gulf of Suez, Egypt, producing since 1957. Most of the oil production comes from the Nukhul sand, which resulted in the depletion of this zone. The depletion of the Nukhul sand creates a challenge for the drilling engineering in terms of the optimum well design and the drilling methodology to implement, which would help reduce the drilling costs and ensures smooth drilling operation for early production. The focus of this paper will be on the ARM block in the Abu Rudeis Field where recent field studies has shown that better production rates can be achieved from drilling horizontal wells as compared to drilling deviated wells. Four horizontal wells were drilled in the ARM block and for all four wells; a pilot hole was drilled in order to determine the unconformable top of Nukhul Sand Formation. The pilot holes that were used to determine the sand top was then plugged and abandoned and side-tracks were drilled for a build-up section whose casing point selection was made based on the pilot hole data. Failure to set casing at the top of the reservoir sand would result in complete mud circulation losses due to the difference in pore pressure between the depleted sand and the pressurized shale above it. The analysis of the nonproductive time including the pilot hole cost, the sticking pipe risk and the possible oil based mud losses ranged +/- 1.8 M$.
This paper highlights the engineering solution and the technology usage of the first reservoir mapping while drilling service in Egypt to land a horizontal well with proactive detection of the casing point in order to eliminate the nonproductive time associated with drilling pilot holes. The main objective is to continue drilling more horizontal wells in order to increase the oil production from the field.
Horizontal and highly deviated wells are increasingly being used in oilfield developments worldwide, with the target to deliver higher oil production rates than conventional completions, optimizing the final field recoverable reserves.
Nukhul Formation in Abu Rudeis Field is a clastic depleted reservoir of Oligo-Miocene age underlying pressurized Miocene Shale of Rudeis Formation. It consists of three sandstone layers intercalated by shale. The sharp thickness variations of Rudeis Basal Shale and Transition Nukhul Formation (TNAF) increase the uncertainty of casing point detection. When it is difficult to proactively predict the location of Top Nukhul due to these structural challenges, complete drilling fluid losses occur when drilling through Top Nukhul into the target sands without adjusting the mud weight and setting the casing at the correct depth.
Treating these complete losses, and hence plugging back to perform a side-track increases hugely the total operational costs and time. Moreover, in order to detect the casing point so far a pilot hole was needed, requiring additional budget and drilling time.
Belayim Petroleum Company (Petrobel) established an integrated team of different disciplines with the aim of identifying an innovative solution to proactively set the casing point exactly at top of depleted zones, reducing horizontal wells operational time and cost and avoiding the use of a pilot hole.
The case history presented includes the first application of the Reservoir Mapping While Drilling service in Egypt as geo-stopping/landing technique in a horizontal well, with the primary objective of use this technology to map TNAF and land at a desired inclination to accurately and proactively set the correct casing depth.
Petrobel developed a new plan to maximize the production from the Abu Rudeis Field, which included an extensive drilling campaign of horizontal wells. The Abu Rudeis Field is one of the oldest fields in the Gulf of Suez, producing mainly from the Nukhul sand reservoir.
Nukhul Formation in Abu Rudeis Field is a clastic depleted reservoir of Oligo-Miocene age underlying pressurized Miocene Shale of Rudeis Formation.
Belayim field is a mature oil field located eastern side of Gulf of Suez onshore and off shore communicated through saddle in Kareem Rudies layers only. This field is being considered to be a giant. start producing since 1955 from Belayim land and from Belayim Marine (first off-shore discovery in Egypt in 1961) since 1962. Main Production is from Miocene sandstone reservoirs in a complexly faulted two anticlines. The large extension of the field accompanied with the presence of fault barriers and the lateral facies variation of sandy shale intercalation have confirmed the non-uniform depletion throughout the field implying slight compartmentalization behavior. The initial reservoir pressure was 4200 psi and has been declining in different manners.
Belayim fields Water injection strategy was to start injection in periphery wells as the pressure depleted. In Belayim marine field modifying the periphery wells locations towards the producing wells through second and third rows and due to injection lines leakage and high cost to replace the lines with new, innovative solutions has to be implemented such as (dump flooding, injection portable units flexible lines ,…… etc ).
In Belayim land field after good understanding of the reservoir and due to the heterogeneity of the reservoir a new strategy was developed by using separated injection pattern in different isolated blocks. Then to improve the sweep efficiency of waterfront the injection of polymer started. Also starting using water disposal wells to support pressure in Belayim land field.
This paper highlights the different ways of solving the problems of water injection in Belayim fields How to optimize water injection and aiming to maintain the production plateau and consequently improve recovery (with optimum cost).
Belayim Marine is one of the largest oil fields in the central Gulf of Suez and the first off-shore discovery in the middle east, in the early sixties. The field is operated by Petrobel, a joint venture between EGPC and IEOC, the cumulative production @ Dec., 2016 was 1596.753 MMSTB.
The field contains several sandstone reservoirs, ranging from Palaeozoic to Miocene age.
The total OOIP is 4150.585 MMSTB, 80% of which is contained in the Kareem Rudeis reservoir, which is being supported by a peripheral water flooding started in the eighties.
Offshore exploration is a costly endeavor that entails multi-million dollar expenditures to acquire synthetic aperture radar data, electromagnetic data, 2-D seismic data, as well as 3-D seismic data to evaluate subsurface structures and systems. However, while these technologies lend an understanding to the geologic structure of subsea systems, these do not address the critical question of the presence of a petroleum system (i.e. charge).
This case study was conducted by Anadarko Petroleum Corporation in their Marco Polo field in the Gulf of Mexico. The project focused on improving the mapping of hydrocarbons from petroleum systems by augmenting seismic with additional technologies such as detailed multibeam bathymetry, side scan sonar, and acoustic backscatter to acquire high-resolution sea floor characterization and ultra-sensitive hydrocarbon detection to provide hydrocarbon detection with a thousand times greater sensitivity than traditional methods.
The high resolution geophysical data significantly improved the ability to locate macroseep sites. Additionally, the ultra-sensitive hydrocarbon system was able to identify hydrocarbons from both macroseepage and microseepage. Thus, hydrocarbons were detected in one hundred percent of the core samples, instead of 10% as found with traditional methods.
While the Marco Polo site focused on macroseepage acquisition the Red Sea case study focused on microseepage acquisition. The Red Sea area that was overlain by 8,000 ft of evaporitic salt and anhydrite sequences that also contained inter-bedded shale sequences. The field was a fractured sub-salt rift basin producing from the Miocene Kareem and Rudeis formations. The client had drilled two producing wells, but had also drilled three dry wells. The thick salt sequence made seismic data difficult to interpret and the extensive faulting added additional risk to the exploration efforts. Given the complex geologic system and the difficulties associated with the seismic imaging, ultra-sensitive hydrocarbon mapping was employed to add understanding to the geologic structure and add clarity to the boundaries of the hydrocarbon accumulations.
Liquid hydrocarbons were detected through the 8,000 ft salt sequence and then mapped across the field indicating areas of high probability of oil locations and areas of low probability. The probability map correctly predicted the previously drilled producing and dry wells. The hydrocarbon survey results also identified two three-way closures in the field as well as a potential fault not identified by seismic data. Subsequent to the study a well was drilled based on the survey results and produced 800 bopd, lending credence to the hydrocarbon probability maps generated by the survey.
The result was the use of new technologies to derisk offshore exploration efforts by more effectively determining the presence of an offshore petroleum system through salt sequences. Additionally, it mapped reservoir boundaries and defined reservoir sweet spots with better pressure and porosity thus enhancing improved production.
El Gogary, Ahmed. F. (Belayim Petroleum Company (Petrobel)) | El-Masry, Hossam. H. (Belayim Petroleum Company (Petrobel)) | Kortam, Mostafa. M. (Petrobel) | El-Rayek, Hany. R. (Belayim Petroleum Company (Petrobel))
Horizontal and highly deviated wells are increasingly being used in oilfield developments worldwide. Large-bore horizontal wells can deliver significantly higher oil production rates than conventional completions, reducing field development costs by allowing reserves to be targeted with fewer wells
Rudies formation in Belayim Land field is a bottom water-drive reservoir with a strong supporting aquifer. it is characterized by its great isotropy and heterogeneity where based on the analysis of SCAL data, it was found that the vertical permeability is nearly equal to horizontal permeability raising the problem of water coning(cresting), earlier water breakthrough situation and masking the oil production by water due to the great difference in mobility
Based on calculation of the critical coning production rates and water control plots it was concluded that the horizontal wells drilled in Rudies formation which are produced with high production rates suffered from extreme water coning problems that raised the necessity for water shutoff procedure to be considered
Field cases presented on this paper explain applications of internal casing packer and blank tubing as a tail pipe in accompanied with downgrading the production rates from horizontal wells for the purpose of zonal water control in the uppermost section of open hole and slotted liner completed horizontal wells in Petrobel
Included in this paper are two different field cases for uncemented water shutoff in horizontal wells that succeeded in decreasing the water cut in the wells from the range of (90-95 %) to the range of (10-30%) implementing a huge increase in the gained net oil towards achieving the maximum recovery. Technical data including well configuration, production performance and casing string are included in the paper. Field operations and lesson learned from each application are also presentedinthispaper
El Haddad, M.I. (Ganoub El-Wadi Petroleum Holding Company (Ganope)) | AbdulGhaffar, M. (Ganoub El-Wadi Petroleum Holding Company (Ganope)) | Fathi, S.A. (Ganoub El-Wadi Petroleum Holding Company (Ganope)) | Elleboudy, M.M. (Ganoub El-Wadi Petroleum Holding Company (Ganope))
Belayim Land field is one of the oldest and largest oil fields in Egypt. It produces oil from many sandstone reservoirs. Oil is produced from 4-30 ohm-m resistivity in Belayim Formation, while to the contrary, in Rudeis Formation, 70-80 ohm-m resistivity is producing water. Rock characterization program was planned for Rudeis Formation using core material. It includes porosity, permeability, thin section description, SEM, wettability, relative permeability and capillary pressure by mercury injection to obtain pore throat size distribution. The wettability of the reservoir rock was determined by Amott method and proved to be strongly oil wet. The wettability controls the position of fluids within the pore network, where in oil-wet the water saturation distributed as poorly connected droplets within the macro-pores and filled the micro-pores.
To simulate the saturation history of the reservoir, restored-state samples at irreducible water saturation were flooded with water to perform electrical resistivity measurements. Non-linear curves were obtained during the electrical resistivity measurements. Two saturation exponents (n) values were proposed to reflect the mechanism of forming continuous water film from the water droplets. The inflection point between the two (n) values was used to determine the resistivity cutoff below which water is produced. In addition, it represents the water saturation cutoff which was confirmed from the calculation of fractional flow of water from relative permeability measurements. The production data confirm the use of variable (n) to monitor the water saturation in oil-wet reservoirs.
An increasing number of deviated wells are being drilled to maximize production and hydrocarbon recovery in the mature reservoirs of the Gulf of Suez (GoS). Successfully drilling a high-angle well in a tectonically disturbed and structurally complex area like the GoS is very challenging, especially in depleted reservoirs. Selecting the optimal mud weight is absolutely essential. Stress orientation and magnitude also have a major impact on wellbore stability.
The region poses significant drilling challenges that vary widely from reactive shale and salt creep to stress-related instability. From the findings of multiple wellbore stability projects we conducted in the GoS, we review the dominant mechanisms of wellbore instability in the GoS. We provide a summary of the failure mitigation measures and an overview of stress magnitude and orientation in the region, demonstrating how it impacts the knowledge of the most stable drilling direction.
Understanding the main causes of rock failure in the GoS resulted in improved drilling efficiency and reduced drilling costs. We show an example, where a new, nearly horizontal (86º) well was successfully drilled through the Asl formation with less than half a day of non productive time during the entire drilling process.
We conclude that acquisition of new, high-quality data would considerably reduce the uncertainty surrounding drilling complex wells in the area and reduce their cost.