Ambient Noise Data Processing to Obtain Group Velocity for Subsurface Structure Identification: Preliminary Research in Hululais Geothermal Field, Sumatra, Indonesia

Hululais area lies in the pull-apart basins of the Ketaun Segment and Musi Segment fault as a part of the Sumatra Fault Zone (SFZ). The boundary normal faults of pull-apart basins play an important role as major discharge zones for geothermal fluid because the extensional stress is concentrated in the boundary normal faults. In order to identify the geothermal reservoir structure in Hululais Geothermal Field (HGF), we introduce the local-scale study of the Rayleigh wave group velocity structure using ambient noise tomography (ANT). The ANT studies were collected using 18 seismometers inside 12 km2 area with a spacing of 125 – 500 meters, deployed across the fault structure for 1 month. More than two thousand Rayleigh Green’s Functions are extracted by cross-correlation at available station pairs. Using the estimated green function in this preliminary research, the group velocity as a function of the period can measure the dispersion curve by using multiple filter technique (MFT) and fast marching surface tomography (FMST) scheme to obtain group velocity images. The tomography result as group velocity image shows the subsurface Rayleigh wave structure variation. The NW-SE main structure is reflected by the contrast velocity structure between the central part and the north eastern-south western sides. The central part shows the low periods which are associated with low wave velocity However the margin of the central part shows the high velocity in all periods. The ANT studies have been efficient in time and cost, however useful in subsurface structure interpretation in Hululais Geothermal Field

Geological Analysis for Slope Stability Using the Rock Structure Rating (RSR) Method and Atterberg Limit at Riau - West Sumatra Cross road Km 165 Harau Subdistrict, Lima puluh Kota Regency, West Sumatra Province

Stability on the slope was considered important for the safety of people who pass through the highway. Failure of slopes on highways can cause losses especially roads had an important role in community activities. The research was located on the Riau – West Sumatra Km 165. The purpose of this research was to find out treatment or mitigation that can be given to the research slope and know the soil classification based on the analysis Atterberg Limit. The research slope was divided into 3 parts using analytical Rock Structure Rating (RSR) method based on different slope conditions. And 1 part of the slope has become soil using the analytical method Atterberg Limit. Treatment or mitigation that can be given to the research slope, namely the use of rock shopandshotcrete based on the RSR diagram and the use of rock embankments to resist landslides

Field Development with Scenario Reactivation of Non-Active Zones Through Reservoir Simulation: A Case Study of The Kappa Offshore Field, West Natuna

This research provides the scenario of a field development plant with the primary goal of acknowledging the reservoir model of Kappa Field in determining the optimum field development scenario to increase the recovery factor. In this research, field development will be carried out by creating scenarios that differentiate certain parameters to see the differences from these scenarios. The main problem in this field is to find out the feasibility of a field that has a history of production from 1986 to 2022 or for 33 years. In addition, the main objective of this research is to determine the reservoir driving mechanism of the Pasir RH-7 layer and determine the best field development scenario to optimize production in the Kappa field. The method used in this study is the reservoir modeling method using production data and reservoir data that has been obtained from the company and then managed using the Petrel Software assisted by Eclipse and MatBal. Before developing field development scenarios, an analysis is carried out using several different methods, including analysis with the decline curve analysis method in determining the remaining recoverable reserves as the validation of Kappa Field's feasibility, identify the driving mechanism of the reservoir, and history matching between history production data with simulation results. Sensitivity analysis of the field development is also conducted through various scenarios, including adding or adjusting well perforation interval, infill well adding, five water injection wells, and four gas injection wells. Other than that, injection gas and water rates in injection wells are also being exercised during the sensitivity analysis. Simulation results show the best scenario of Kappa Field is ten infill wells and four injection wells with a water injection rate of 1000 BWPD and gas injection rate of 1 MMSCF/d, giving the optimum recovery factor result of 39.33% from oil reserves. The results of this research will have a positive impact on the development of the Kappa field in order to increase production from fields that have been producing since 1986 and stopped production in 2019

Analysis The Effect Of Column Height Variation On The Perfomance Of Increased Building Structure

The consequences of these earthquake waves cause damage to buildings ranging from light damage to heavy damage. Dealing with the case, it is necessary to plan and implement earthquake-resistant building structures, especially in high-rise buildings. Another factor that needs to be considered is the function of the room which affects the column height when the column height is different and it causes uneven stiffness from the ground floor to the top. The aim of this study was to find out the effect of variations in column height on the performance of multi-storey building structures in terms of shear forces, floor drift and buckling load (Pc). The method used in this study was the response spectrum method. The spectrum response is the maximum response of a Single Degree of Freedom (SDOF) structural system, both acceleration, velocity and displacement due to the structure being loaded by a certain external force. Before carrying out the analysis using the response spectrum method, a structural model was undertaken by varying the column height on the 1st floor into 3 variations. Dealing with the results of the analysis on the building structure model with varying column height on the 1st floor, it indicated that the higher the column the maximum base shear force value increases. The higher the 1st floor column, the maximum floor deviation value increases. The higher the column the value of the column slenderness ratio increases and the Euler buckling load decreases

1D Geomechanical Model For Wellbore Stability in Z Field, Y Well Sanga Sanga Working Area, Kutai Basin

This research is about 1D geomechanical model for wellbore stability in Z Field, Y Well Sanga Sanga Working Area, Kutai Basin where wells have been drilled. The Purpose of this Research is to analyze the stability of the well starting from knowing the stress regime that occurs, predicting the occurrence of wellbore failure, and determining safe mud weight window for next drilling. The method use in this Research is a numerical modelling method using log data and drilling data that has been obtained and then managed using Techlog Software. The result of this Research show the magnitude of mechanical properties of the rock that have been obtained, then in general the stress regime that occurs in the Z Field formation is the normal regime even though the strike slip and reverse regime are inserted at a certain depth, then based on the prediction results of failure in this well is wide breakout, which in general occurs in lithology with sandstone, finaly safe mud weight window can be estimated properly, so that it can be used for further well drilling. This research is about 1D geomechanical model for wellbore stability in Z Field, Y Well Sanga Sanga Working Area, Kutai Basin where wells have been drilled. The Purpose of this Research is to analyze the stability of the well starting from knowing the value of the mechanical properties of the formation, the stress regime that occurs, predicting the occurrence of wellbore failure, and determining safe mud weight window for next drilling. The method use in this Research is a numerical modelling method using log data and drilling data that has been obtained and then managed using Techlog Software. The result of this Research show the magnitude of mechanical properties of the rock that have been obtained, then in general the stress regime that occurs in the Z Field formation is the normal regime even though the strike slip and reverse regime are inserted at a certain depth, then based on the prediction results of failure in this well is wide breakout, which in general occurs in lithology with sandstone, finaly safe mud weight window can be estimated properly, so that it can be used for further well drilling

Geomorphology and Geology Studies Using Digital Elevation Model (DEM) Data In the Watershed Area of Kampar Regency, Riau Province

This research was conducted in the area of ​​Kampar Regency, Riau Province .it was located at coordinates including 01° 00' 40" - 00° 27' 00" South Latitude and 100° 28' 30"- 101° 14' 30" East Longitude. The purpose of this study was to determine the geological condition of the watershed, and it was determined the geomorphological condition of the watershed, to determine the number of divisions of the watershed, to determine the relationship between the watershed and rainfall, to determine the geological and geomorphological relationship with the watershed in the study area. The method used starts from field sampling, core description, distribution analysis of geological data, geomorphology, watershed analysis, and analysis of rainfall. Based on the analysis of the distribution of geological data in the research area, there were 12 geological formations from the results of geological mapping, namely: the Sihapas Formation, the Telisa Formation, the bekasap formation, the Bahorok Formation, the Farmer Formation, the Manggala formation, the Talang Akar formation, the Telisa Atas formation, the Palembang Tengah formation, Basement, members of the Lower Palembang formation (Air Berakat), members of the Upper Palembang formation (Muara Enim). In subsurface geology there were 8 well points in the study area, 2 correlations were carried out, namely the 1st correlation between CR-04, CR-03, CR-01, CR-02, CR-08, and the 2nd correlation between CR-05, CR-06, CR- 07. Geomorphological conditions were divided into 4 namely lowland areas, low hill areas, hilly areas, and high hill areas. The watersheds in the research area were divided into 2 watersheds, namely the Kampar and Siak watersheds. Watershed rainfall observations in the study area for 5 years from 2015 – 2019 were located at 5 different stations, with fluctuating rainfall intensit

Lineament Density and Implications for the Distribution of Ground Fissures After 2021 MW 7.3 Flores Sea Earthquake on Kalaotoa Island, Indonesia

A 7.3 MW earthquake occurred at 11:20 am on December 14, 2021, in the Flores Sea, and the main shake was centered ±100 km north of Maumere, Indonesia, with a depth of 14.3 km, antecedent a landslide. This research consists of two stages, namely: quantitative data collection in the form of tectonic lineament density measurements using Shuttle Radar Topography Mission (SRTM) data which is extracted manually using GIS-based applications, and qualitative data in the form of field observations which include strike-dip measurements of rocks, lithological data, morphological conditions, ground fissures, and the distribution of damage caused after 2021 earthquake. This study focused on analyzing the value of lineament density, its correlation to the history of seismicity and surface lithological conditions, and the impact after the 2021 earthquake damage. The lineaments of the southern area are dominated by NE – SW orientation along with various lithological conditions and with lineament density values very low – very high. A crack width from 0.5 to 112 cm, and a vertical offset occurs with a depth of up to 270 cm. The western area is dominated by lineament with an orientation NE – SW with a crack width from 8 to 18 cm, and there is a vertical offset with a depth of up to 24 cm. The distribution of ground fissures in the Garaupa Raya area is categorized as low. The orientation of the northern area lineament is relatively NW – SE directional and the lineament density value is categorized as low. Horizontal displacement with an orientation of NW – SE is found at the port of Kalaotoa Island, Kawawo village with measured crack width of ±17 cm, an observable horizontal offset from 15 to 24 cm, and a vertical offset of ±12 cm with a trend of movement towards the south

Machine learning prediction of tortuosity in digital rock

Physical rock property measurement is an important stage in energy exploration, both for hydrocarbons and geothermal sources. The value of physical rock properties can provide information about reservoir quality, and one of these properties is tortuosity. Tortuosity is an intrinsic property of porous materials that describes the level of complexity of the porous arrangement when a fluid passes through it. Conventionally, tortuosity values are measured through laboratory analysis and numerical simulation, but these measurements can take a long time. An alternative method for measuring tortuosity is using machine learning with a convolutional neural network (CNN). A CNN is a type of deep neural network designed to analyze multi-channel images and has been applied successfully to classification and non-linear regression problems. By training a CNN on a dataset of digital rock samples that have been simulated using numerical computation to obtain their tortuosity values, it is possible to demonstrate that CNNs can accurately predict the tortuosity of digital rock. The result is that the CNN model can predict tortuosity values with the Xception model being the most accurate with the lowest RMSE value of 0.90962

Analysis of Water Availability in the Upper Siak Basin Using the GR2M Model Application

The Siak watershed is one of the critical watersheds, where natural disasters such as floods, landslides and erosion often occur in this area. The Siak watershed has 4 main sub-watersheds, namely the Tapung Kanan sub-watershed, the Tapung Kiri sub-watershed, the Mandau sub-watershed and the Siak Hilir sub-watershed. The existence of these 4 sub-watersheds is also not able to meet the water needs of the community due to the rapid development of the region which will then cause the demand for water to continue to increase in line with the rate of population growth, especially in the Siak watershed area. Fulfillment of food needs and population activities is always closely related to the need for water. These demands cannot be avoided, but must be predicted and planned for the best possible use. The purpose of this study is to describe the application of the GR2M modeling and the amount of raw water availability in the Upper Siak Watershed. The research method used is descriptive quantitative with data collection techniques in the form of map data, rain data, climatology data and field discharge data. And the research location is in the Upper Siak Watershed, namely the Tapung Kiri Sub-watershed. The results of the study show that 1) GR2M modeling can be applied to the Tapung Kiri Sub-watershed with an R2 performance of 0.41 with a satisfactory interpretation, a correlation coefficient (R) of 0.67 with a strong interpretation, and an efficiency coefficient (CE) of 0.59 with sufficient optimization interpretation. The reliable discharge obtained based on the GR2M modeling data for the availability of drinking water (Q99%) in the Siak Hulu watershed is 15.69 m3/second

Front matter JGEET Vol 08 No 02 2023

    &nbsp