Search Repository STTMIGAS Balikpapan

Dalam Proses Pemboran sumur tidak selalu berlangsung sesuai dengan yang
diharapkan, dengan melakukan analisa post-drill pada pemboran sumur HL-7
diharapkan dapat memperoleh hasil sesuai target yang diinginkan. Adapun metode
yang digunakan yaitu analisa Pore Pressure Fracture Gradient (PPFG) dengan
tujuan mengetahui permasalahan pemboran yang dapat terjadi selama proses
pemboran, mengetahui penempatan casing point yang tepat serta penentuan mud
weight yang tepat pada setiap interval kedalaman pemboran. Untuk mendapatkan
hasil tersebut digunakan perhitungan menggunakan software DrillWorks Predict.
Penelitian ini dititikberatkan pada analisa Pore Pressure Fracture Gradient
(PPFG), dengan menggunakan data wells Surrounding diantaranya data master
log berupada drilling event (lost circulation, connection gas, stuck pipe, gain,
dll.), Data RFT (Repeat Formation Tester) atau PT-FA (Pressure Test Fluid
Analysis), serta data log tali kawat. Hasil analisa PPFG menunjukan bahwa
terdapat zona yang berpotensi menyebabkan drilling hazard diantaranya: pada
kedalaman 2191 ft, 2926 ft, 6125 ft yang menunjukan zona low pressure, pada
kedalaman 6343 ft sampai dengan 8100 ft menunjukan proyeksi zona
overpressure, karakteristik overpressure yang terjadi diketahui disebabkan oleh
adanya dissequilibrium compaction.
Setelah dilakukan penentuan Pore Pressure Gradient dan Pressure Fracture
Gradient, dilakukan penentuan interval casing point dan mud weight program
yang akan digunakan dalam setiap interval pemboran yang akan dilakukan. Pada
dasarnya prinsip yang digunakan dalam desain casing point pada grafik pore
pressure fracture gradient ialah Bottom to Top Design. Berdasarkan analisa dan
perhitungan yang dilakukan, penempatan casing point untuk intermediate casing
dengan ukuran casing 9-5/8 inci terletak pada kedalaman 6340 ft, dan casing
point pada surface casing dengan ukuran 13-3/8 inci terletak pada kedalaman
1750 ft. Adapun mud weight yang digunakan pada setiap interval kedalaman
pemboran diantaranya interval 0 - 150 ft dilakukan dengan cara ditumbuk maka
dilakukan tanpa menggunakan lumpur pemboran, interval kedalaman 150-1750 ft
digunakan mud weght sebesar 8.6 ppg, interval kedalaman 1750 6340 ft
digunakan mud weight sebesar 9.8 ppg dan interval kedalaman 6340 8100 ft
menggunakan mud weight sebesar 14.1 ppg

In the process of drilling the well does not always proceed as expected, by
conducting a post-drill analysis on the drilling of the HL-7 well, it is hoped that
the results according to the desired target can be obtained. The method used is
Pore Pressure Fracture Gradient (PPFG) analysis to know drilling problems that
can occur during the drilling process, knowing the right casing point placement,
and determining the right mud weight at each drilling depth interval. To obtain
these results, calculations using the DrillWorks Predict software ware used.
This research focuses on Pore Pressure Fracture Gradient (PPFG) analysis,
using wells Surrounding data including master log data in the form of drilling
events (lost circulation, gas connection, stuck pipe, gain, etc.), RFT data(Repeat
Formation Tester) or PT-FA (Pressure Test Fluid Analysis), as well as wireline
log data. PPFG analysis results show that there are zones that have the potential
to cause drilling hazards including at a depth of 2191 ft, 2926 ft, 6125 ft which
indicate as low-pressure zone, at a depth of 6343 ft to 8100 ft indicates an
overpressure zone projection, the characteristics of the overpressure that occur
are known to be caused by the presence of compaction disequilibrium.
After determining the Pore Pressure Gradient and Pressure Fracture
Gradient, the casing point interval and the mud weight program are determined to
be used in each drilling interval to be carried out. The principle used in the
design of the casing point on the pore pressure fracture gradient graph is Bottom
to Top design. Based on the analysis and calculations performed, the placement
of the casing point for the intermediated casing with a casing size of 9-5/8 inches
is located at a depth of 634ft, and the casing point for the surface casing with a
casing size of 13-3/8 inches is located at a depth of 1750 ft. The mud weight used
at each drilling depth intervals of 150-1750 ft used mud weight of 8.6 ppg, depth
interval of 1750-6340 ft used mud weight of 9.8 ppg and a depth interval of
6340-8100 ft using a mud of 14.1 ppg.