SR08 made, and petrography evidence was found to correlate this type of organic matter. Organic facies distribution in the passive Once organic facies maps were generated for each genetic margin of the Basin: Coastal sequence of the passive margin; original HI from mature rocks limit movement application were determined by compositional model (Cooles et al., 1986) to improve HI contours in organic facies lateral distribution maps. Landann C. Escorciaa, Linda Montillaa y Nubia Santiago Finally, organic facies vertical distribution was studied to establish a PDVSA Exploración, Puerto La Cruz, Anzoátegui, an interaction within the coastal border movement. Marine and terrestrial organic facies limit could be different from the *escorcialc@.com transgression to the regression into the passive margin. Besides that, coherence between this distribution and palobatymetric maps Copyright 2014, ALAGO. were studied. This paper was selected for presentati on by an ALAGO Sci entific Committee following review of information contained in an abstract submitted by the author(s). Results and Discussion Three (3) organic facies were defined in Barinas-Apure Basin Introduction where distribution is related to orogen position and sediment Lateral and horizontal variations of a source rock in a petroleum direction during passive margin. Two organic facies present a system can be established in a sedimentary basin by using organic high marine influence and are located in the northern part of the facies analysis. Through this type of analysis, fluid-rock correlations basin, deposited under neritic conditions: ABMI with the highest are more accurate. Furthermore, if the potential of the source rock HI, and ABMII with the lowest HI component. The other organic is established, liquid and gas volumes of generation can be inferred. facies has a terrestrial predominance; it is located in the southern part and was deposited under transitional to continental paleo- Specifically, for the Barinas-Apure Basin, this study allows bathymetries: ABTI. Principal characteristics and areal distribution understanding the distribution and variation of the source rock are described: within the passive margin. Some inferences about the coastal line movement were made; due to geochemical changes that occur ABTI: 254 mgTOC/grock is the typical hydrogen index of this in this transition, with a positive correlation with paleo-bathymetric organic facies. Petrographic studies, prove that it is composed maps. by amorphous (60 to 70%), herbaceous (5 to 10%), woody (10 to 20%), and coally (5 to 10%), with a predominance of woody Experimental content and vitrinite. There are some samples of mycrite content in Organic facies (Haoet al., 1993) are determined by mapping initial terrestrial environment as an evidence of terrestrial organic input. potential of a possible source rock in a delimited stratigraphic TOC distribution goes from poor to medium with a same pattern sequence. Tectonostratigraphic chart of Barinas Apure Basin made from HI distribution. by Santiago et al., 2014 were used to establish petroleum potential in depositional units and stratigraphic sequences. From this first ABMI: in this organic facies, hydrogen index is 634 mgTOC/ step, only two depositional units had some potential intervals of grock. Petrographic studies, it is composed by amorphous (70 to source rock: UDII and UDIII. UDII is a passive margin and UDIII is 90%), herbaceous (5 to 10%), woody (10 to 25%), and coally (5 the beginning of the active margin. However, this study will focus to 10%), with a high level of amorphous content, possibly related into the passive margin (UDII, Figure 1) to initial marine organic matter. Moreover, there are evidences of dinoflagellates. This organic facies is located in the northern part of the basin.

ABMII: hidrogen index from this organic facies is 399 mgTOC/ grock. Petrographic analysis show: amorphous (60 to 90%), herbaceous (5 to 30%), woody (10 to 30%), and coally (0 to 10%). Besides that, there are evidences of dinoflagellates and amorphous fluoresce as well; located restrictively into the basal sequences of the transgressive sequence in the south western. Figure 1. Tectonostratigraphic chart of Barinas-Apure Basin(Santiago et al., 2014) Distributions of the organic facies developed during the passive margin are shown in Figure 2 (ABTI, ABMI y ABMII). The movement Lithostratigraphically the UDII is an Albian transgressive sequence of coastal line in the passive margin can be observed in Figure 2 of aggrading sandy facies; then, that turned progressively into a evolution of the distribution of the organic facies during passive shaly facies until the maximum depth in Coniacian age at 88,8 m.a. margin phase. There is a progressive advance of the marine line represented by MFS_4 surface (Figure 1). during transgression and an advance of terrestrial line during regression. More to the point that, ABMII organic facies is restricted Based on stratigraphic sequences for the passive margin described to basal sequences; its higher potential could be thought as paleo- before, initial Hydrogen index (HI) values were mapped for each depocenter from the rifting phase in the basin and/or as a result of M.F.S. in Figure 1. Then, relationships between the data were a climate control.

Figure 2. Organic facies distribution in genetic sequences from the passive margin of Barinas-Apure Basin. From SG V to basal deposits (Figure 1).

Conclusions Organic facies methodology used in the Apure Barinas Basin’s source rock intervals refined the potential of the basin to generate hydrocarbons. Moreover, the study of marine and terrestrial organic facies interaction into small stratigraphic levels, allowed the evaluations of eustatics controls related with coastal limit movement within the passive margin.

References Cooles, G.P., Mackanzie, A.S., Quigley, T.M., 1986, Calculation of petroleum masses generated and expelled from source rocks, in: Leythaeuser, D., Rullkötter, J. (eds.), Advances in Organic Geochemistry, 10, 235–245.

Hao F, Chen J, Sun Y. y Liu Y.,1993, Application of organic facies studies to sedimentary basin analysis: a case study from the Yitong Graben, China. Organic Geochemistry20-1, Enero, 27-42.

Santiago, N., Bellizzi, L., Escorcia, L., Hernández,M.,Hernández, Z.,, J.,Marcano, J.,Moya, M.,Oliveros, R.,Oropeza, Y.,Parra, K., Peña, Y., Rivas, Y., 2014, Proyecto Evaluación del Sistema Petrolífero Apure-. Informe interno PDVSA.