The Lauwerszee Trough isanorthwest-trendingsub-basinwithinthe Southern PermianBasinandlies inthe onshorearea ofnortheastern Netherlands. Referred to asthe 'GoldenLane'Trend, itisthe classicalLower PermianRotliegendgasplayofthe Netherlands,consistingofthe prolific,high net-to-gross sandstonereservoirs ofthe SlochterenFormation. Traps aretilted extensionalfault blockst hatentrapgass ourced from the CarboniferousCoalMeasures. The overlyingR otliegendT enBoerClaystonea ndU pperPermianZechstein evaporitic rocksprovide the top andlateralseals for the fault traps.Int hiss tudy3 0fault traps werea nalysed inw hich 22 weref oundto haveg asaccumulations. Trapfill is controlled primarily bySlochterens and-on-sandj uxtaposition leakage across af ault; however,someg as accumulationsasm apped appeart obe filled deepert hant hisl eakpoint andrequiresand-on-sandf ault seal. Retained fault-sealgascolumns arerelatively small andmostly less than60m withoneexception of95m.Sevenp otentialSlochterens and-on-sandf ault-zoneseals werei dentified int hiss tudy. The analysiso fthese fault traps revealed three possiblecriteria thatmaypromotethe development ofsuch fault seals:(1) juxtaposition against atight,shale-rich interval;(2) small isolated sand-on-sandj uxtaposition area ( , 25000 m 2 )t ypically associated withfault lengthsless than1km; or (3) occurrence ofacomplexnarrow fault zone.However,some sealingfault segments areassociated withstructuralinterpretation/mappinguncertainty. Minor mapchangesmay eliminateperceived sand-on-sandf ault-zoneseals andexplaintrapfill byconventionalfault juxtaposition.
Multi-fault analysis is an ExxonMobil stochastic tool for analysing the impact and sensitivities of stratigraphic uncertainty and variability on cross-fault leakage of hydrocarbons in faulted traps. This juxtaposition-based method provides quantitative prediction of hydrocarbon contact levels through a complex system of structural spills and juxtaposition leak points in traps with stacked reservoir systems and one or more faults. Validation of the Multi-fault analysis technology was carried out by comparing pre-drill predictions to post-drill results from 41 faulted exploration prospects drilled from 1994-2001. Of the 41 prospects, 29 were valid tests in which we made 22 successful predictions. Of the 22 successful outcomes, 11 were discoveries and 11 were dry wells. Some of the dry wells were drilled assuming the presence of sealing fault-zone material to trap hydrocarbons despite a Multi-fault analysis failure prediction. The seven Multifault failures comprise four predicted successes that were failures and three predicted failures that were successes. Most of the Multi-fault prediction failures can be attributed to data quality and uncertainty; however, some may be associated with sealing fault-zone material. Other considerations in fault seal analysis (i.e. dip leak along faults and sealing fault zone materials), model input uncertainties, and using drill-well learnings are also discussed.Fault seal analysis has been used since the 1960s to predict the impact of faults on the flow or storage of fluids in hydrocarbon reservoirs. Initial attempts at fault seal analysis concentrated on defining pressure or hydrocarbon column height differences across faults and using those observations to infer the sealing behaviour of faults (e.g. Smith 1966). Such studies used cross-sections constructed at high angles to the strikes of faults to understand the connections of permeable units across the faults. If disparate pressures or hydrocarbon fluid contacts were observed where a cross section provided evidence of a potential sand-to-sand juxtaposition, then it was assumed that the fault zone itself sealed in order to isolate the sands on each side of the fault from each other. However, the cross-section approach gives only a one-dimensional look at a fault (i.e. a single profile view along the fault), and the sand-to-sand juxtapositions across it, and as such, failed to define possible juxtapositions everywhere along the strike length of a fault. As well, early attempts at fault seal analysis were hampered by map quality and accuracy. In the 1960s and 1970s, depth-structure maps were constructed from variable quality two-dimensional seismic data and/or from well penetration data (formation or sequence tops), making derivative analyses, such as fault seal analysis, of suspect quality.With the development by Allan (1989) of a method for making fault plane profiles (so-called Allan diagrams), sand-to-sand juxtapositions along the length of faults could be defined in much better detail. Fault plane profiles are cross-sections ...
Unbalance of the three-phase currents in photovoltaic (PV) systems may depend on structural aspects of the installation, the effect of partial shading, or both. In this paper, a number of unbalance indicators are calculated starting from data that are measured during experimental analyses on a real building-integrated PV system that represents different types of unbalance. Detailed information is obtained from indices that identify the balance and unbalance components that are also in the presence of waveform distortion. These indices extend the current definitions of unbalance given in the power quality standards. The results show that the unbalance cannot be considered negligible, even with no singlephase inverters and is more significant if nonlinear loads add a contribution to both harmonic distortion and unbalance seen from the distribution transformer.
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