Analisis dan perencanaan semen pemboran dengan sistem semen ringan untuk mengatasi soft formation pada Lapangan Taruna
S Soft formation yang terkadang ditemui selama kegiatan pemboran sumur migas mempunyai beberapa ermasalahan yang terjadi, seperti loss circulation danrusaknya formasi bila menggunakan metode konvensional dalam menanganinya. Oleh karena itu dibutuhkan penanganan khusus. Solusi yang digunakan dalam menghadapi soft formation adalah dengan penggunaan sistem semen ringan sekaligus menjadi tujuan target dalam penelitian ini, dimana sistem ini akan menurunkan tekanan hidrostatik dari kolom fluida semen tersebut sehingga mencegah invasi cement slurry masuk ke formasi sekaligus menjaga tekananformasi agar tidak rusak dan sistem thixotropic semen ringan untuk mencegah loss circulation pada formasi. Sodium silicate, bentonite dan cenospheremerupakan light additive material yang akan digunakan dalam mencari desain sistem semen ringan terbaik sehingga didapatkan nilai konsentrasi yang tepatdengan kebutuhan formasi di lapangan Taruna yang dipengaruhi faktor suhu, tekanan formasi, kedalaman target penyemenan dan temperature gradient.Metode yang digunakan adalah percobaan di laboratorium dengan perbandingan dan penyeleksian berbagai desain terhadap konsentrasi chemical additive sehingga didapatkan desain terbaik untuk kasus di lapangan Taruna dengan 4 sumur sebagai objek penelitian yaitu : X16-04, X23, X17-01, X17-02. Test yang dilakukan di laboratorium pun bervariasi mengikuti standar internasional API RP 10B-2 dan ISO 10426-2 dengan mempertimbangkan performa sistem semenringan tersebut melalui pemeriksaan densitas, rheology test, fluid loss test, free fluid test, sediment test, thickening time test, compressive strength test, ultrasoniccement analyzer, dan cement hydration analyzer. Dari berbagai percobaan dan pengujian di laboratorium telah disimpulkan dan didapatkan 8 desain terbaik yaitu: 13 3/8 inci casing tail, 9 5/8 inci casing scavenger, 9 5/8 inci casing tail, 7 inci casing lead, 7 inci casing tail, 7 inci casing scavenger, 5 inci liner scavenger, danthixotropic cement plug dengan 3 densitas bubur semen ringan : 11.5, 12.5, dan 13.5 ppg dan dilengkapi berbagai kelakuan yang terjadi didalam sistem semenringan tersebut baik dari faktor chemical additive didalamnya maupun faktor eksternal lainnya. Pada sistem semen ringan ini terdapat dampak negatif yangdihasilkan sehingga memerlukan chemical additive tambahan agar dapat meningkatkan performa bubur semen dengan ditambahkannya fluidloss additivedan gas block serta chemical lainnya.
S Soft formation which is sometimes encountered during oil and gas well drilling activities has several problems that occur, such as loss circulation and formationdamage when using conventional methods in handling it. Therefore special handling is needed. The solution used to deal with soft formation is to use alightweight cement system as well as being the target in this study, where this system will reduce the hydrostatic pressure of the cement fluid column so as toprevent the invasion of cement slurry entering the formation while maintaining the formation pressure so as not to be damaged and the system thixotropiclightweight cement to prevent loss circulation to the formation. Sodium silicate, bentonite and cenosphere are light additive materials that will be used in findingthe best lightweight cement system design so that the right concentration values are obtained with formation requirements in the Taruna field which areinfluenced by temperature, formation pressure, depth of the target cementing and temperature gradient. The method used is a laboratory experiment withcomparison and selection of various designs of chemical additive concentrations so that the best design for the case in the Taruna field with 4 wells as researchobjects is: X16-04, X23, X17-01, X17-02. Tests conducted in the laboratory also vary according to international standards API RP 10B-2 and ISO 10426-2 by considering the performance of the lightweight cement system through densityinspection, rheology test, fluid loss test, free fluid test, sediment test, thickening time test, compressive strength test, ultrasonic cement analyzer and cement hydration analyzer. From various experiments and tests in the laboratory it has been concluded and obtained 8 best designs, namely: 13 3/8 inches tail casing, 9 5/8 inches scavenger casing, 9 5/8 inches tail casing, 7 inches lead casing, 7 inches tail casing, 7 inch scavenger casing, 5 inch scavenger liner, and thixotropic cement plug with 3 density lightweight cement slurries: 11.5, 12.5, and13.5 ppg and are equipped with various behaviors that occur in the lightweight cement system both from chemical additive factors inside and other externalfactors. In this lightweight cement system there are negative impacts that are generated so that additional chemical additives are needed in order to improvethe performance of the cement slurry by adding fluidloss additives and gas blocks and other chemicals.