Najmah-Sargelu Formations of Kuwait show considerable potential as a new unconventional hydrocarbon play and produces mainly from fractures. The key uncertainties which affect the productivity are the nature and distribution of permeable fracture networks, and the limits of oil accumulation.
This paper presents the results from whole-rock elemental analysis of three cored wells in UG field. The main objectives of this study are to use high-resolution elemental chemostratigraphy to gain a better understanding of the detailed stratigraphy and correlation of the Najmah-Sargelu Formations, to assess the chemo-sedimentology for determining the intervals of high organic content, to estimate the mineralogy of the sequence using an algorithm developed for an analog formation in North America; and to determine the most likely intervals to contain fractures, using a brittleness algorithm.
A clear chemo stratigraphic zonation is recognized within the Najmah-Sargelu Formation. The larger divisions are driven mainly by inherent lithological variation. The finer divisions are delineated by more subtle chemo stratigraphic signals (K2O/Th and Rb/Al2O3 ratios) and preservation of organic matter (high V, Ni, Mo, and U abundances). Zones of alternating brittleness and ductility are clearly identified within the interbedded limestones and marlstones of Najmah-Sargelu Formation.
Two unexpected but important features of the Najmah-Sargelu limestones were elucidated by the elemental data. Brittle, high-silica spiculites, with virtually no clay or silt, are more common than previously recognized from petrophysical logs and core descriptions in the upper Najmah limestones. In addition, the limestones adjacent to the spiculites tend to contain bitumen as pore-filling are recognized by the trace metal proxies. Ternary plots of V, Ni, and Mo differentiate the combinations of kerogen and bitumen present in the Najmah-Sargelu Formations.
The clarity and sensitivity of the chemostratigraphic signals are sufficient to enhance formation evaluation, and can also assist borehole positioning using the RockWiseSM ED-XRF instrument at wellsite.
Ozyurtkan, Mustafa Hakan (Istanbul Technical University) | Altun, Gursat (Istanbul Technical University) | Ettehadi Osgouei, Ali (Istanbul Technical University) | Aydilsiz, Eda (Istanbul Technical University)
Static filtration of drilling fluids has long been recognized as an important parameter for drilling operations. Since the standard laboratory testing procedures only consider static conditions, the filtration and cake properties under continuous circulation and dynamic borehole conditions are not usually well determined. Therefore, the measurement of dynamic filtration is particularly important in order to mimic actual downhole conditions.
An experimental study has been carried out by the ITU/PNGE research group to characterize the dynamic filtration properties of clay based drilling fluids. This study is an impressive attempt to figure out the dynamic filtration phenomena of clay based muds. The experimental results obtained from a dynamic filtration apparatus (Fann Model 90) are reported in this study.
Bentonite and sepiolite clays based muds formulated with commercial additives have been investigated throughout the study. Numerous dynamic filtration histories with test duration of 45 to 60 minutes at temperature conditions ranging from 150 to 400 oF, and a differential pressure of 100 psi have been applied to muds. Three key parameters namely spurt loss volume, dynamic filtration rate (DFR), and cake deposition index (CDI) have been determined to characterize the dynamic filtration properties of mud samples.
Results have revealed that bentonite based muds have better dynamic filtration properties than those of sepiolite muds at temperatures up to 250 oF. However, they have lost their stability over 250 oF. Furthermore, formulated sepiolite based muds have remarkable dynamic filtration rates and cake depositions above 300 oF. To sum up, the experimental results of this study point out that sepiolite based muds might be a good alternative to drill wells experiencing high temperatures, particularly in deep oil, gas and geothermal wells.
This paper aims to study the miscibility features of CO2 miscible injection to enhanced oil recovery from Thani-III reservoir. A Comprehensive simulation model was used to determine multi contact miscibility and suitable equation of state with CO2 as a separate pseudo component using one of the industry's standard simulation software. Experimental PVT data for bottom hole and separator samples including compositional analysis, differential liberation test, separator tests, constant composition expansion, viscosity measurements and swelling tests for pure CO2 were used to generate and validate the model. In addition to that, simulation studies were conducted to produce coreflooding and slimtube experimental models, which were compared with the conclusions drawn from experimental results. Results of this study have shown comparable results with the lab experimental data in regards to minimum miscibility pressure (MMP) calculation and recovery factor estimation, where the marginal errors between both data sets were no more than 7% at its worst. Results from this study are expected to assist the operator of this field to plan and implement a very attractive enhanced oil recovery program, giving that other factors are well accounted for such as asphaltene deposition, reservoir pressure maintenance, oil saturation, CO2 sequestering and choosing the most appropriate time to maximize the net positive value (NPV) and expected project gain.
Hassan, Hany Mohamed (Petroleum Development Oman) | Al-hattali, Ahmed Salim (Petroleum Development Oman) | Al Nabhani, Salim Hamed (Petroleum Development Oman) | Al Kalbani, Ammar (Petroleum Development Oman) | Al Hattali, Ahmed (Petroleum Development Oman) | Rubaiey, Faisal (Petroleum Development Oman) | Al Marhoon, Nadhal Omar (Petroleum Development Oman) | Al-Hashami, Ahmed (Petroleum Deveopment Oman)
A cluster area "H" consists of 4 carbonate gas fields producing dry gas from N-A reservoir in the Northern area of Oman. These fields are producing with different maturity levels since 1968. An FDP study was done in 2006 which proposed drilling of 7 additional vertical wells beside the already existing 5 wells to develop the reserves and enhance gas production from the fields. The FDP well planning was based on a seismic amplitude "QI" study that recommended drilling the areas with high amplitudes as an indication for gas presence, and it ignored the low amplitude areas even if it is structurally high. A follow up study was conducted in 2010 for "H" area fields using the same seismic data and the well data drilled post FDP. The new static and dynamic work revealed the wrong aspect of the 2006 QI study, and proved with evidence from well logs and production data that low seismic amplitudes in high structural areas have sweet spots of good reservoir quality rock. This has led to changing the old appraisal strategy and planning more wells in low amplitude areas with high structure and hence discovering new blocks that increased the reserves of the fields.
Furthermore, water production in these fields started much earlier than FDP expectation. The subsurface team have integrated deeply with the operation team and started a project to find new solutions to handle the water production and enhance the gas rate. The subsurface team also started drilling horizontal wells in the fields to increase the UR, delay the water production and also reduce the wells total CAPEX by drilling less horizontal wells compared to many vertical as they have higher production and recovery. These subsurface and surface activities have successfully helped to stabilize and increase the production of "H" area cluster by developing more reserves and handling the water production.
This paper describes the results of the feasibility study of an arcticoffshore platform concept sponsored by ConocoPhillips. This concept consists ofa Conical Piled Monopod (CPM) platform, shown in Figure 1, assisted by an IceWorthy Jack-up rig, Gemini, to drill development wells in Multi Year iceconditions as illustrated in Figures 2 and 3. The Gemini design is beingjointly developed by ConocoPhillips and Keppel Offshore and Marine TechnologyCentre Pte Ltd based in Houston. Gemini is equipped with two drill rigsthat can simultaneously or individually cantilever above the well slots locatedon the deck of the CPM. The key benefit of Gemini lies in extending thedrilling season from a few months during ice free season to several monthsbeyond the ice free period.
The study was carried out at Granherne Limited under ConocoPhillips'supervision between March 2010 and February 2011. A topsides operatingload of 5,000 tonnes was assumed, instead of 70,000 tonnes (or more)corresponding to a two drill rig stand alone drilling and production CPM. Thefeasibility of a stand alone drilling and production CPM was presented inanother paper at Icetech12 in September 2012.
The study concludes that a Gemini assisted CPM is feasible for iceconditions in the Canadian Beaufort Sea. The ice loads were calculated,in consultation with Ken Croasdale, a well known specialist in this discipline.Ice conditions assumed in this study were in accordance with ISO-19906, namely,12m thick level ice and a very rare 25m thick ice island event. No icemanagement was assumed. A Gemini assisted CPM offers a much lighter platformcompared to a standalone CPM or Gravity Based Structure.
ConocoPhillips has a patent pending on the CPM. ConocoPhillips andKeppel Offshore have patent(s) pending on the Ice Worthy Jack Up drilling rig,Gemini.
A numerical modeling procedure was developed, using the finite-elementsimulator ABAQUS/Standard, to predict the local buckling and post-bucklingresponse of high strength pipelines subject to combined state of loading. Thenumerical procedures were validated using test data from large-scaleexperiments examining the pure bending and local buckling of high strengthlinepipe. The numerical simulations were consistent with the measuredexperimental response for predicting the peak moment, strain capacity,deformation mechanism and local buckling response well into the post-yieldrange.
A parametric study on the local buckling response of high strength plainpipelines was conducted. The influence of pipe diameter to wall thickness ratio(D/t of 40, 60 and 80), pipe segment length to diameter ratio (L/D of 3.5, 5, 7and 12), yield strength to tensile strength ratio (Y/T of 0.7, 0.8 and 0.9) andinitial geometric imperfections on the local buckling response was examined.The loading conditions included internal pressure and end rotation. Mechanicalresponse parameters examined included moment-curvature, ovalization, localstrain and modal response.
This paper characterizes the processes that presently occur during freeze-upin the Alaskan Beaufort and Chukchi Seas, based on joint-industryinvestigations conducted in 2009-10, 2010-11, and 2011-12. The studies weredesigned to address five specific objectives: (1) describe the ice conditionsthat evolve during the freeze-up and early winter seasons; (2) locate and mapfeatures of potential importance for offshore exploration and productionactivities, including ice movement lines, leads, polynyas, first-year ridgesand rubble fields, and multi-year floes; (3) locate and quantify ice pile-upson natural shorelines and man-made structures; (4) correlate significantchanges in the ice cover with the corresponding meteorological conditions; and(5) compare present-day freeze-up processes with those that occurred in the1980s. Each study included an analysis of meteorological data, ice charts, andsatellite imagery in concert with a series of aerial reconnaissance missions.The study findings are presented in seven categories: (1) air temperatures, (2)first-year ice growth, (3) the timing of freeze-up, (4) landfast ice, (5)multi-year ice, (6) ice pile-ups, and (7) extraordinary ice features discoveredoff the Chukchi Sea coast.
This paper characterizes the spatial and temporal variability of riveroverflooding on the sea ice and related pipeline and facility siting concernsfor the nearshore region of the Alaskan Beaufort Sea. This phenomenon occurseach spring during a brief period when river discharge precedes the break-up ofthe landfast sea ice. The river water flows on top of the grounded and floatingsea ice, and can spread several kilometers offshore and encompass vast areas.The overflood waters drain through holes and discontinuities in the ice, andcan create large scour depressions on the sea floor when the drainage rate ishigh. These so called "strudel scours" can constitute a significant designconsideration for subsea pipelines.
Onshore and offshore pipelines may be subjected to mechanical damage duringinstallation and operation due to environmental loads, external forces andthird parties. The type and severity of pipe damage may influence operational,repair and intervention strategies. For conventional pipelines, the assessmentof mechanical damage plays a role in the development of integrity managementprograms that can be of greater significance for pipeline systems located inremote, harsh environments. The current study highlights the effect of plaindents and interaction of plain dents with girth weld on pipe mechanicalresponse using continuum finite element methods. The modelling procedures arecalibrated with available physical datasets and also demonstrate excellentcorrelation with third party simulations. Confidence in the numericalsimulation tool provides a basis to evaluate the effects of mechanical damagethrough a broader parameter study and assess effects on fatigue lifeperformance.
This article, written by Editorial Manager Adam Wilson, contains highlights of paper SPE 156098, "Deal With Startup and Commissioning Threats and Challenges at an Early Stage of the Project for a Successful Handover and Project Completion," by M. Al-Bidaiwi, SPE, M.S. Beg, SPE, and K.V. Sivakumar, Qatar Petroleum, prepared for the 2012 SPE International Production and Operations Conference and Exhibition, Doha, 14-16 May. The paper has not been peer reviewed.