Africa (Sub-Sahara) A drillstem test was performed on the Zafarani-2 well--located about 80 km offshore southern Tanzania. Two separate intervals were tested, and the well flowed at a maximum of 66 MMscf/D of gas. Statoil (65%) is the operator, on behalf of Tanzania Petroleum Development Corporation, with partner ExxonMobil Exploration and Production Tanzania (35%). The FA-1 well--located in 600 m of water in the Foum Assaka license area offshore Morocco--was spudded. The well targets Eagle prospect Lower Cretaceous resources. Target depth is 4000 m. Kosmos Energy (29.9%) is the operator, with partners BP (26.4%),
Sand production has always been a challenge for oil operators worldwide. Several parameters can lead to sand production, including poor cementing material in the reservoir, high production rates, and high drawdown applied to an unstable zone. The subject field consists of 105 wells; 90 of these wells are oil producing wells, 11 are water injection wells, two are dump flood wells, and two are water source wells. The primary challenge was to perform a gravel pack job on a high permeability water source well to deliver a planned rate of 25,000 bwpd.
A study for the formation, the area, and the history of gravel packing in the operator fields was made to provide the optimum solution for the target well. The well was categorized as a critical well because of the various challenges and because of its importance to the operator in supplying the field with the injection water, which was down for months. The completion specifications, sizes, and the pumping techniques were agreed upon with the operator and the critical well review team. The well suffered from high losses resulting from the high permeability and long interval. The fluid losses had to be controlled before running in with the completion equipment and pumping the gravel pack treatment to avoid premature screenout.
After perforating the pay zone, the well, as expected, suffered from high losses. These losses were controlled by pumping several non-damaging fluid loss pills until the losses were suitable for running the gravel pack assembly in the hole. The treatment was pumped in alternating stages of clean fluid and slurry fluid to aid in the displacement of the proppant in the annular space and to minimize the risk of bridging.
Premium screens (6-5/8 in. with 175 micron filter) were used along with a 40/60 proppant. A 5-in. wash pipe was used to force the majority of the fluid in the slurry to remain in the casing/screen annulus to maximize sand transport, rather than leaking off through the screen and into the screen base pipe/wash pipe annulus.
The treatment was successfully pumped, covering the 500 ft of screens and leaving excess volume of sand covering the blanks. The well was completed with an electrical submersible pump (ESP) and is producing 11,500 bwpd with no reported issues.
The injection in the field is now online after being down for five months as a result of shutting down the well.
Kortam, Mostafa Mahmoud (Petrobel) | Siso, Samir (Petrobel) | Abbas, Nelly Mohamed (Schlumberger Egypt) | Salah, Ahmed (Petrobel) | Hesam, Atef (Petrobel) | Cilli, Andrea (Petrobel) | Kamar, Ahmad (Schlumberger Egypt) | Khafagy, Fatmaelzahraa (Schlumberger Egypt)
The development of low quality reservoirs such as; low permeability, marginal assets, and unconventional resources has a several cost challenges pushing the industry toward maximizing the potentiality and optimizing the strategies of such high risk plays.
Petrobel has a discovered one of such challenged asset and successfully conducted a comprehensive study to set the best development strategy to unleash this potential. SIDRI Area is a relatively new settlement with a reasonable hydrocarbon potential according to petrophysical analysis. The target formation of SIDRI wells is a sedimentary rock with granitic facies that consist of a series of tight conglomerates over an oil/water column of more than 900m. The pore system of this rigid and stiff formation consists of a micro natural fractures network with secondary cemented porosity. The production is mainly governed these tiny natural fractures that have a permeability as low as 0.1-0.5 md. Despite this tightness these series are separated by nonporous sections that occasionally exhibit as barrier and may introduce layering or subdivision of pay, however in sometimes permit a vertical communication between productive sections. Performed Cuttings analysis such as XRD, thin-sections showed a variety of minerals composition representing different lithology which in turn complicates the characterization of such reservoir.
On top of the unique mineralogy, the executions of fracturing treatment of SIDRI wells include multiple other challenges. The higher reservoir temperature and the formation depth cause a great constraint in terms of pumping rate and pressure. Besides, the non-availability of pumping equipment of high Horsepower restricts the pump rates and also limits the utilization of slick water frac. Even the nature and the quality of crude oil is quite challenged since it is a heavy black oil type and its composition contains high number of asphaltenic compounds accordingly the opportunity of creating sludge with treatment fluids is highly likely. The oil water viscosity ratio at reservoir condition represents a weighted obstacle for oil recovery that should be overcome.
The basic concept of applying hydraulic fracturing for these kinds of reservoirs is very simple, however the execution to get much more production improvement is quite difficult. Particularly the main idea here is to conduct a cost effective fracturing treatment with economical wisdom principle that can lead to achieve a greater oil recovery with best profitable model.
Fahmi, Adel (Belayim Petroleum Company) | Attia, Alaa (Belayim Petroleum Company) | El-Tokhy, Medhat (Belayim Petroleum Company) | Saber, Sharif (Belayim Petroleum Company) | Madkour, Alaa (Belayim Petroleum Company)
The present work is intended to summarize some observations derived from the structural seismic interpretation carried out in Abu Rudeis/ Sidri field, based on the recently acquired OBC-2010. A new 3D OBC Seismic survey was acquired recently in the area in 2010 Showing a new and more interesting exploratory blocks in the Miocene (Nukhul Fm) and Pre-Miocene (Lower Senonian, Turonian, Cenomanian and Nubia sandstone) in addition to, the new un-conventional reservoir (fractured Igneous intrusions and meta sediments).
The study area is located within the north western of Red Sea- Gulf of Suez. The rift system is interpreted started around the late Oligocene and continue throughout the Miocene, and undertook extension in N650 W direction, nearly perpendicular to pre-existing WNW trending pan African shear Zone fabrics in the crystalline basement of the Sinai African plate.
The interpreted fault pattern is characterized by a series that comprises two sets of faults. The first corresponds to the northwest-southeast trend, which bound the study area from the South, offset fault segments throughout ramp relay structures, with maximum throws around 1000 m, juxtaposing Eocene-Paleocene sediments from the down-thrown block (basin wards) against the basement in the up-thrown block, the second system trends northeast-southwest and is interpreted as a later evolution of the rifting this last mainly strike slip and, the pre-existent northwest-southeast trending off-set fault segments by breaking the ramp relay structures.
As a fruitful result of the new 3D-OBC seismic survey, a positive result of the drilling good discovery proved the presence of the hydrocarbon potentialities and proved the conventional and unconventional reservoir.
The summary of these observations regarding the tectono-stratigraphic evolution of Abu Rudeis field area advocates both, remaining field exploration and development opportunities.