Sequence Stratigraphy And Sedimentary Facies Study Of F2,Zarzaitine Oil Field,Algeri

Zarzaitine oil field is located in 1500km southeast of Algiers,the capital of Algerian,the east of Sahara,the Yili Zi(ILLIZI)basin near the border of Libyan,the average ground elevation of 565m.The drilling of oil-bearing strata of Zarzaitine oil field including F2,F4,F6 of the Devonian and A,B2a,B2b,B4,B6,B8,D4 of the Carboniferous,the main oil-bearing strata is F4 layer of the Devonian.In recent decades,with the depth development of the main strata F4,F2 layer also attracted the attention of the people and we have a certain foundation in the tectonic evolution,the distribution of stratigraphic thickness and the reservoir,etc currently.But the problem we faced with is that the information on the main layer F4 is enough,while on the non-main layer F2 is less,the complete well log data is very litter and mostly in the lower parts constructing.The test data is also litter,therefore is quite difficult to carry out geology and reservoir studies for the non-main layer.In this paper,under the guidance of the the theory of high resolution sequence stratigraphy and sedimentology,combined with logging and core data,we research on the F2 reservoir such as on sedimentary facies and sequence framework and other aspects of the study.The main deposition of F2 is delta,other part is turbidite fan deposits.By the analysis of the Cores and logs phase,we determine the delta microfacies types:subaqueous distributary channel,mouth bar,sheet sand,distal bar,distributary clearance.Turbidite fan microfacies types:turbidity channels,turbidity sheet sand,semi-deep sea mud.Based on the Cores and according to the rock-electrical response characteristics,we establish two logging template of microfacies types which form the two different sedimentary.With the knowledge of high resolution sequence stratigraphy,we gived high-precision division on the stratigraphic framework of the F2 layer.According to characteristics of the core,the multiwell correlation and curve characteristics,we selected five typical interface,divided into four short-term cycles in the F2 layer.Lower strata Expressed as typical anti-rhythmic in the logging curve and it shoule be delta deposition;well sites north of the upper strata are rhythm on the well logs,Bouma sequence development in the core and it should be turbidite fan deposition.Use of high-resolution sequence stratigraphy principles and analysis techniques,divide the sequence stratigraphy of single well and correlate the sequence stratigraphic between wells,we establised high-precision stratigraphic framework of the F2 layer,and discussed the identification of sedimentary transfer surface and the comparison method of the sequence stratigraphic.With information integrated,the paper carried out sedimentary microfacies distribution and the prediction under constraints of sequence stratigraphic framework,analysised of the space distribution,development and evolution of sedimentary facies and sand body distribution law in short-term cycles.Integrated use of the single well,the well-connection deposition profile and logging facies,conduct to favorable reservoir zone prediction hierarchical segments of the F2 layer and provide the scientific basis for the exploration and development.