Tekstur batuan karbonat dikenal dengan tingkat kompleksitas yang tinggi. Sehingga untukmemahaminya dibutuhkan perhatian yang lebih mendetil. Mengingat batuan karbonat ada bermacam-macam dan terdapat pengaruh deformasi rongga sekunder, dimana hal tersebut berkaitan langsung dengan nilai properti, yakni porositas dan permeabilitas. Berdasarkan nilaipengukuran properti pada sampel batuan inti yang sering dijadikan acuan, kadang masih menimbulkan kesalahan pada hasil permodelan dan keadaan sebenarnya. Oleh karena itu dibutuhkan metode yang dapat menghubungkan antara analisis kualitatif (fasies pengendapan)dan kuantitatif (korelasi nilai properti). Analisis fasies pengendapan dilakukan dengan acuan data wireline log, sample batuan inti, biostratigrafi, dan petrografi. Kemudian untuk analisis kuantitatif (rock typing) dilakukan dengan acuan nilai properti (porositas, permeabilitas, saturasi air, dan volume shale). Dalam menentukan metode kuantitatif yang paling tepat untuk digunakan dalam penelitian ini, penulis menyuguhkan metode Windland dan Hydraulic FlowUnit. Pada penelitian ini bertujuan untuk mendapatkan hubungan model fasies pengendapan dengan pembagian kelompok rock typing pada formasi Kujung unit I, lapangan “Betta”, Cekungan Jawa Timur Utara. Formasi Kujung Unit I top hingga bottom pada daerah penelitianmengindikasikan adanya 13 parasekuen. Terdapat beberapa lithofacies yaitu mudstone hingga grainstone, dan shale. Berada pada lingkungan pengendapan laguna dan open shelf dimana situasi eustasy konstan sehingga mendukung pertumbuhan reef patch. Nilai properti yangterkandung pada interval ini antara lain porosity berkisar 1.3% - 31.3% dan permeabilitasnya berkisar 0.04 mD hingga 1042 mD. Sehingga menghasilkan beberapa kelompok reservoir yang diberi ranking satu (1 - excellent), dua (2 – good), tiga (3 – poor), dan empat (4 – very poor) berdasarkan pengelompokan batuan dari kesamaan nilai flow unit (HFU) dan ukuran ronggayang saling terkoneksi (R35).

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The texture of carbonate rock is known as a high level of complexity because it has several varieties and the effect of secondary porosities, such as vugs and crystallization. So that is directly involved to its properties value. However, the properties that are measured on core samples as a reference are often unmatched when it comes to modelling vs. actual condition. So, it is necessary to get the right method that can match between qualitative (depositional

facies) and quantitative analysis (properties correlation). Depositional facies interpretation is

controlled by wireline log data, core data sample, biostratigraphy, and also petrography report.

Later on, the quantitative analysis (rock typing) determined by combining reservoir properties

values, which are porosity, permeability, water saturation, clay volume. The next step is to get

the right quantitative analysis method for this research, we provide Windland and hydraulic

flow unit method to identify rock typing of carbonate reservoir. The objective from this research is to find correlation between depositional facies and its quality of carbonate Kujung unit I reservoir groups that located in “Betta” field, North East Java basin. Kujung Unit I formation from top to bottom in the research area indicates the presence of 13 parasequences.

There are several lithofacies namely mudstone to grainstone and shale. It is in a lagoon deposition environment and open shelf where the eustasy situation is relatifly constant thus supporting the growth of reef patches. The property values contained at this interval include porosity ranging from 1.3% - 31.3% and its permeability ranges from 0.04 mD to 1042 mD. Thus producing several reservoir groups ranked one (1 - excellent), two (2 - good), three (3 - poor), and four (4 - very poor) based on rock typing analysis based on the similarity of flow unit value (HFU) and the size of interconnected pores (R35).