Stratigraphic relationship

Stratigraphic relationship

Two types of contact: Conformable and Unconformable.

Conformable: Unbroken deposition, no break or hiatus (break or interruption in the continuity of the geological record). The surface strata resulting is called a conformity.

Two types of contact between conformable stata: Abrupt contacts ( Directly separate beds of distinctly different lithology, minor depositional break, called Diastems) Gradational contact (Gradual change in deposition, mixing zone).

Unconformable: Period of erosion/non-deposition. The surface stratum resulting is called an unconformity.

Unconformity. A surface of erosion between rock bodies that represents a significant hiatus or gap in the stratigraphic succession. Therefore, unconformity-bounded units are bodies of rocks bounded above and below by significant unconformities. They are composed of diverse types of any kind or kinds of rocks, but the lithologic properties of these rocks, their fossil content, or the chronostratigraphic span of the rocks on either side of the bounding unconformities are significant only to the extent that they serve to recognize the bounding unconformities

Four types of unconformity

Angular unconformity . An unconformity in which the bedding planes above and below the unconformity are at an angle to each other.

Disconformity The contact between younger and older beds is marked by visible, irregular erosional surfaces. Paleosol might develop right above the disconformity surface because of the non-deposition setting.

Paraconformity The bedding plans below and above the unconformity are parallel. A time gap is present but there is no erosion, just a non-deposition period.

Nonconformity Relatively young sediments are deposited right above older Igneous or metamorphic rocks.

Link to www.foraminifera-biostratigraphy.blogspot.com

SEMI-ANALYTICAL APPROACH OF OPTIMUM VIBRATION FREQUENCY DETERMINATION THAT GIVES MAXIMUM IMPROVEMENT OF RESERVOIR ROCK POROSITY

PROCEEDINGS, INDONESIAN PETROLEUM ASSOCIATION
Thirtieth Annual Convention & Exhibition, August 2005

SEMI-ANALYTICAL APPROACH OF OPTIMUM VIBRATION FREQUENCY DETERMINATION THAT GIVES MAXIMUM IMPROVEMENT OF RESERVOIR ROCK POROSITY

Mursalim Mardin*
Tutuka Ariadji*

ABSTRACT

Declining production in oil recovery operations is a major concern in the oil industry. Each of commonly applied EOR methods has a number of limitations as well as some undesirable results. Vibration stimulation technologies are an alternative method in improving production and increasing recovery in which the vibration is thought to facilitate production by, in one view of diminishing capillary forces; reducing adhesion between rocks and fluids; or causing oil droplets to cluster into "streams" that flow with the waterflood, and the other view of enlarging pore volume.

Various laboratory investigations have been conducted to find out the effect of high and low vibration frequency on the reservoir rock properties. A study of low-frequency waves is of special interest because of the potential for reservoir stimulation by surface-based vibrators. Reservoir resonant frequencies should be selected to get the maximum improvement in reservoir rock properties.

The results of the laboratory research show that effect of vibration causes an increase of effective porosity up to 9.17%. Optimum frequency is 15 Hz in all of the experiments. Furthermore, this investigation also tries to seek a semi-analytical equation for optimum frequency based on the laboratory result. The general resultant equation has the format:

ö = A Sin ù × f + ö _o av . ( )

where “A” is constant value, “ω” is constant value, “ ö_o” is porosity before vibration (%), _“öav” is

porosity after vibration (%) and “ f” is frequency (Hz).

Key words: improving production, recovery improvement, EOR, vibroseismic stimulation, vibration, effective porosity, resonant frequencies, optimum frequency, semi-analytical approach

* Institute Technology Bandung

WATERFLOOD OPTIMATION ON AN INVERTED 7-SPOT PATTERN USING CORE, WELL LOG, AND SEISMIC DATA IN POPO AREA, MINAS FIELD, CENTRAL SUMATRA BASIN

PROCEEDINGS, INDONESIAN PETROLEUM ASSOCIATION
Thirtieth Annual Convention & Exhibition, August 2005

WATERFLOOD OPTIMATION ON AN INVERTED 7-SPOT PATTERN USING CORE, WELL LOG, AND SEISMIC DATA IN POPO AREA, MINAS FIELD, CENTRAL SUMATRA BASIN

Andrew Ivan Julius Sitorus*
Edy Sunardi*
Abdurrokhim*
Henri S.M.P. Silalahi**

ABSTRACT

Reservoir characterization involves the quantification, integration, reduction, and analysis of Geological, Petrophysical, Seismic and Engineering data. The principal goal of Reservoir characterization is to derive a spatial understanding of interval heterogeneity. The final product of this analysis (reservoir characterization) is a 3D reservoir model which is largely a function of a stratigraphic framework.

Interpreted 3D reservoir model may give such important information to the next step of exploration or development for an oil company. In a development area for instance, we can choose using steamflood or waterflood (for a secondary recover method) etc., depending or considering the 3D reservoir model.

The research was held on an inverted 7-spot pattern in Popo Area, Minas Field. Waterflood method is used in the research area. This secondary method yields unsatisfying result, and from a Field Trial that was held before this research showed that there is still some areas have not been swept yet by the waterflood and there is still remaining oil which is economically potential. Why? That is a good question.

The purpose of this research is to discuss what the problem is and how to handle or optimize this kind of problem.

The research used three main data they are core, correlation wells, and 3D seismic data. Through the integration of these data we know that there is one main reason, which is the heterogeneity of the reservoir. Stratigraphic and structural aspects are the main controller for the waterflood “dysfunction”. To solve this problem, actually there is more than one option that can be considered, but the research focuses on one. That is an optimation well. The optimation well is made in the unswept area or zone, hoping that the potential remaining oil can be taken.

* University of Padjadjaran

** P.T. Caltex Pacific Indonesia

PRODUCTION OPTIMIZATION IN SUBANG GAS FIELD USING RESERVOIR SIMULATION

PROCEEDINGS, INDONESIAN PETROLEUM ASSOCIATION
Thirtieth Annual Convention & Exhibition, August 2005

PRODUCTION OPTIMIZATION IN SUBANG GAS FIELD USING RESERVOIR SIMULATION

Amelia Dwi Saputri*

ABSTRACT

Subang field is a dry gas reservoir with combination of drive mechanism, depletion and water drive. Initial gas in place is 970.3 BSCF with CO2 content of 21.53 %. Until 30 April 2004, cumulative gas production is 35.0 BSCF or ± 3.6 % from initial gas in place with flow rate 114 MMSCFD from 13 wells those started producing in February 2002.

In order to fulfill gas requirement of 140 MMSCFD in 8 - 10 years from Subang field, production optimization through reservoir simulation study is done by using Petroleum Workbench simulator. The Subang field simulation modeling is using regular grid corner point type with 70 x 70 x 6 dimension with 118 m x 119 m size for each cell. History matching process is done using saturation matching method by adjusting the gas and water relative permeability curve (krg and krw) parameters. There are nine scenarios run until 31 December 2024, with variation of wells stimulation, additional of perforation interval and additional of new wells with production flow rate controlled at 150, 100, and 80 MMSCFD. All those scenarios were run with minimum bottom hole pressure at 345 psi, and minimum field flow rate at 15 MMSCFD.

From those simulation result and economic analysis show that the most effective scenario is third scenario which has the biggest recovery factor of 87.25 %, able to produce up to 150 MMSCFD for 7 years 4 months, and has the most profitable economic indicators with for each gas price of US $ 1.5, 2, 2.5 / MMBTU, this scenario has NPV US $ 10,8 MM, US $ 63,4 MM, US $ 113,4 M, ROR 14 %, 22 %, 28 %, PIR 1.9, 3.4, 4.9, and POT for 6.2 years, 4.5 years, 3.8 years respectively.

* Trisakti University

EVALUATION, REDESIGN OF GAS LIFT VALVE, AND OPTIMIZATION OF GAS INJECTION ON WELLS K-18 AND S-15 IN KS FIELD PERTAMINA DOH JBB

PROCEEDINGS, INDONESIAN PETROLEUM ASSOCIATION
Thirtieth Annual Convention & Exhibition, August 2005

EVALUATION, REDESIGN OF GAS LIFT VALVE, AND OPTIMIZATION OF GAS INJECTION ON WELLS K-18 AND S-15 IN KS FIELD PERTAMINA DOH JBB

Kurniawan Febrianto*

ABSTRACT

Gas Lift System has been installed as artificial lift method for wells K- 18 and S-15 at KS field. Based on production data, well K-18 produces 236 BFPD with 547 MSCFD of gas injection rate at pressure of 2241 psi. When gas injection rate is increased up to 1.1 MMSCFD, liquid rate will increase up to 240 BFPD or 2% at optimum condition. Well S-15 produces 1524 BFPD with gas injection rate of 500 MMSCFD at pressure of 2094 psi. Optimum point will be obtained by injecting 0.4 MMSCFD of gas and it will produce 1524 BFPD of liquid.

However, redesign of Gas Lift Valve (GLV) is one of alternative effort to increase liquid rate from well. Redesign GLV on K-18 shows operating pressure (Pso) is designed at 710 psi which is 3% lower than existing condition of 735 psi. New design of GLV suggests to add valve from 5 to 6. GLRt condition does not change before and after redesigning, but volume of gas injection will decrease by 57% from 600 MSCFD to 260 MSCFD.

GLV redesign on well S-15 shows that _Pso is designed at 850 psi that is 21% higher than 700 psi as the existing condition. New GLV design suggests to use only 4 valves which is less one valve from the existing one. GLRt in redesign of well S-15 will change from 500^SCF/BBL to 2000^SCF/BBL and it will result of increasing gas injection from 500 MSCFD in existing condition become 2700 MSCFD for the new design.

Gas injection performance can be optimized by using Pipesim-2000. At well K-18, existing gas injection rate optimum of 1.1 MMSCFD and pressure 2241 psi will produce liquid at rate of 240 BFPD. After redesigning the GLV, the volume of liquid production will increase by 13% to 271 BFPD with only 0.5 MMSCFD of gas injection as optimum condition. While GLV redesign at well S-15 indicates that optimum injection gas rate is 0.25 MMSCFD at pressure 2094 psi and it will give optimum point at 1576 BFPD. The liquid rate is 3% higher than optimum condition before redesigning which is 1524 BFPD with 0.4 MMSCFD of gas injection rate.

Based on this evaluation, redesign of GLV, and optimization of gas injection on wells K- 18 and S-15 will give result of increasing liquid production and injection gas rate can be managed efficiently.

* Trisakti University