Publish Date
30 Nov -0001
<![CDATA[Abstract. This study evaluates hydrostatic pressure, equivalent circulating density (ECD), bottom hole circulating pressure (BHCP), and fracture pressure as controlling factors of lost circulation in Well X Pad B. The study used a quantitative descriptive method based on secondary drilling data, including mud log, mud weight, flowrate, rheology, well geometry, leak-off test information, and lithology. Pressure parameters were calculated along true vertical depth and interpreted using the drilling window concept. The results show that the well was generally drilled under overbalanced conditions; however, the margin between ECD/BHCP and fracture pressure became narrower in the deeper interval, particularly around 5,400-6,600 ftTVD. The critical interval is dominated by limestone and carbonate lithology interpreted as porous, fractured, vuggy, or brittle. Under this condition, annular pressure loss during circulation increases ECD and BHCP, allowing mud to enter fractures or secondary pores. The recommended control is to increase mud weight gradually to 14 ppg, reduce flowrate in critical intervals, and apply selective lost circulation material. Abstrak. Penelitian ini mengevaluasi tekanan hidrostatik, equivalent circulating density (ECD), bottom hole circulating pressure (BHCP), dan tekanan rekah formasi sebagai faktor pengendali kejadian loss circulation pada Sumur X Pad B. Metode yang digunakan adalah deskriptif kuantitatif berdasarkan data sekunder pengeboran, meliputi mud log, mud weight, flowrate, reologi lumpur, geometri sumur, data leak-off test, dan litologi. Parameter tekanan dihitung terhadap true vertical depth dan dianalisis menggunakan konsep drilling window. Hasil penelitian menunjukkan bahwa sumur secara umum berada dalam kondisi overbalance, tetapi margin antara ECD/BHCP terhadap tekanan rekah semakin menyempit pada interval bawah, terutama sekitar 5.400-6.600 ftTVD. Interval kritis tersebut didominasi litologi limestone dan karbonat yang ditafsirkan berpori, berekahan, vuggy, atau brittle. Pada kondisi tersebut, rugi tekanan annulus saat sirkulasi menaikkan ECD dan BHCP sehingga lumpur lebih mudah masuk ke rekahan atau pori sekunder. Pengendalian direkomendasikan melalui kenaikan mud weight bertahap menjadi 14 ppg, penurunan flowrate pada interval kritis, dan penggunaan lost circulation material secara selektif.]]>
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