Browsing by Author "Senadhira, AMADM"

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item: Conference-Full-text
Analysing the relationship between skin and formation damage of an oil well (time depended)
(Department of Earth Resources Engineering, 2016-07) Ruwanpathirana, RS; Nagasinghe, RV; Welagedara, WWVP; Wickrama, MADMG; Senadhira, AMADM; Ratnayake, NP; Vijitha, AVP; Hemalal, PVA
The concept of skin and formation damage play a vital role in productivity of an oil well. The objective of this study is to introduce the effect of skin into the well flowing equation in transient state. The effect of formation damage zone on the well flowing pressure was introduced to the original solution of diffusivity equation by considering three scenarios. In the first scenario it was assumed that oil is flowing through the reservoir with average (effective) permeability. In the second scenario it was assumed that the oil is flowing with the permeability of reservoir till the boundary of formation damage zone and within the altered zone, oil is flowing with the permeability of damage zone. The third scenario is similar to the second scenario, however it was assumed that the oil is flowing within the altered zone with an average permeability. By considering the difference between calculated reservoir permeability for all three scenarios and assumed values, scenario three was selected as the most suitable way to introduce the effect of skin in to the well flowing equation in transient condition.
item: Conference-Full-text
Analysing the Relationship Between Skin and Formation Damage of an Oil Well (Time Depended)
(2016-08-22) Ruwanpathirana, RS; Nagasinghe, RV; Welagedara, WWVP; Wickrama, MADMG; Senadhira, AMADM; Ratnayake, NP; Vijitha, AVP
The concept of skin and formation damage play a vital role in productivity of an oil well. The objective of this study is to introduce the effect of skin into the well flowing equation in transient state. The effect of formation damage zone on the well flowing pressure was introduced to the original solution of diffusivity equation by considering three scenarios. In the first scenario it was assumed that oil is flowing through the reservoir with average (effective) permeability. In the second scenario it was assumed that the oil is flowing with the permeability of reservoir till the boundary of formation damage zone and within the altered zone, oil is flowing with the permeability of damage zone. The third scenario is similar to the second scenario, however it was assumed that the oil is flowing within the altered zone with an average permeability. By considering the difference between calculated reservoir permeability for all three scenarios and assumed values, scenario three was selected as the most suitable way to introduce the effect of skin in to the well flowing equation in transient condition.
item: Conference-Full-text
Designing and evaluating a casing program for petroleum wellbores
(2014-07-11) Wijesinghe, KADR; Hewavitharana, TD; Mahsoom, MSM; Wickrama, MADMG; Senadhira, AMADM; Ratnayake, NP
Due to high operational and financial risks associated with the investments in the petroleum industry, all precautions are taken by the operators to achieve a safe and cost effective well completion. Casing design of a drilling program is a critical element which contributes greatly to safety and cost of the operation. The objective of this research was to develop a casing design program which enables the user to evaluate casing design proposed or implemented in a drilling campaign. The developed casing design program consists of sequential criteria to select casing setting depth and establish optimum casing strength. Knowledge on local pore pressure gradient and facture gradient are essential to select the casing setting depths. Since both the factors are regional stratigraphy dependants, casing setting depth selection was designed in the way it allows user to assign variables for these parameters. Developed casing design program was validated with the casing design done by Rahman, S. Sand Chilingar, G. V(1995). Validation results shows that the casing design of Rahman and Chilingar and the casing design done with the use of developed program are having similar casing setting depths except in the case of conductor casing.
item: Conference-Full-text
Designing and evaluating a casing program for petroleum wellbores
(Department of Earth Resources Engineering, 2013-07) Wijesinghe, KADR; Hewavitharana, TD; Mahsoom, MSM; Wickrama, MADMG; Senadhira, AMADM; Ratnayake, NP; Hemalal, PVA
Due to high operational and financial risks associated with the investments in the petroleum industry, all precautions are taken by the operators to achieve a safe and cost effective well completion. Casing design of a drilling program is a critical element which contributes greatly to safety and cost of the operation. The objective of this research was to develop a casing design program which enables the user to evaluate casing design proposed or implemented in a drilling campaign. The developed casing design program consists of sequential criteria to select casing setting depth and establish optimum casing strength. Knowledge on local pore pressure gradient and facture gradient are essential to select the casing setting depths. Since both the factors are regional stratigraphy dependants, casing setting depth selection was designed in the way it allows user to assign variables for these parameters. Developed casing design program was validated with the casing design done by Rahman, S. S and Chilingar, G. V(1995). Validation results shows that the casing design of Rahman and Chilingar and the casing design done with the use of developed program are having similar casing setting depths except in the case of conductor casing.
item: Conference-Full-text
Development of a Pore Pressure and Fracture Pressure Gradient Prediction Model for few exploration blocks in Mannar and Cauvery Basins, offshore Sri Lanka
(2015-08-14) Jayasinghe, JMSTW; Kurukulasuriya, AC; Jayasinghe, WMTU; Wickrama, MADMG; Senadhira, AMADM; Ratnayake, NP
Availability of a pore pressure and fracture pressure gradient prediction model for petroleum well drilling is a basis for safety, cost effectiveness and the efficiency of the overall drilling program. Petrophysical data and measured pressure data of four wells previously drilled in the Mannar basin and Cauvery basin were reviewed to establish such a model for few petroleum exploration blocks in Sri Lanka. The pore pressure gradient prediction strategies used for the analysis are, Hottman and Johnson method, Ben Eaton method and D-exponent method. Hubbert and Willis method, Ben Eaton method and Matthews and Kelly method are the fracture pressure gradient prediction strategies used. Area specific variables including Poisson ratio and matrix stress coefficient were determined prior to fracture pressure gradient prediction. After a statistical analysis and comparison with well log data, a combination of Hottman and Johnson method and D-exponent (Eaton) method was selected as the best suited pore pressure gradient prediction model for the drilling area. The analysis of fracture pressure gradient strategies found that the Ben Eaton method is the best suited method for the area. After determining the suitable prediction methods, the Petrel software was used to visually interpret and analyze the results obtained. The research findings will help for future drilling operations and well planning in the specified area in Mannar and Cauvery basins.
item: Conference-Full-text
Development of a pore pressure and fracture pressure gradient prediction model for few exploration blocks in Mannar and Cauvery basins, offshore Sri Lanka
(Department of Earth Resources Engineering, 2014-07) Jayasinghe, JMSTW; Kurukulasuriya, AC; Jayasinghe, WMTU; Wickrama, MADMG; Senadhira, AMADM; Ratnayake, NP; Hemalal, PVA
Availability of a pore pressure and fracture pressure gradient prediction model for petroleum well drilling is a basis for safety, cost effectiveness and the efficiency of the overall drilling program. Petrophysical data and measured pressure data of four wells previously drilled in the Mannar basin and Cauvery basin were reviewed to establish such a model for few petroleum exploration blocks in Sri Lanka. The pore pressure gradient prediction strategies used for the analysis are, Hottman and Johnson method, Ben Eaton method and D-exponent method. Hubbert and Willis method, Ben Eaton method and Matthews and Kelly method are the fracture pressure gradient prediction strategies used. Area specific variables including Poisson ratio and matrix stress coefficient were determined prior to fracture pressure gradient prediction. After a statistical analysis and comparison with well log data, a combination of Hottman and Johnson method and D-exponent (Eaton) method was selected as the best suited pore pressure gradient prediction model for the drilling area. The analysis of fracture pressure gradient strategies found that the Ben Eaton method is the best suited method for the area. After determining the suitable prediction methods, the Petrel software was used to visually interpret and analyze the results obtained. The research findings will help for future drilling operations and well planning in the specified area in Mannar and Cauvery basins.
item: Conference-Full-text
An exploratory factor analysis on issues and constraints in Sri Lankan aggregate quarry industry
(Department of Earth Resources Engineering, University of Moratuwa, 2021-12) Kodithuwakku, KKSN; Munaweera, SPM; Thanojan, T; Jayasundara, DRT; Jayawardena, CL; Senadhira, AMADM; Wickrama, MADMG; Dissanayake, DMDOK; Jayawardena, CL
Mining activities are influenced by stakeholders such as regulators, operators, service providers, customers, residents, and other interest groups. The governing bodies seem to fail to adopt a stakeholder inclusive approach to gain the balance between the interest of the stakeholders and the organisational plans and revenues. Such issues are known at the surface level, but no solid quantitative approach has been used to scientifically prove their existence and associations. Thus, this study aims to find the issues with statistical evidence. Convenient sampling was used due to time restrictions and new work norms to pick a substantial number of respondents. A numerical assignment and logical ordering to qualitative data were done to perform the quantitative analysis. Factor analysis was used to find the principal components and the variables which mainly loaded the components showed significant interpretable correlations. The most significant factors associated with issues in quarry operations and management are found in terms of quality, reliability, and usage of monitoring, application of safety measures, quarry type based hazardous conditions, planning and maintaining quarry activities, combatting drilling issues via site planning, use of initiation technique by quarry type, the impact of environmental and social issues, handling public complaints and strategies to improve quarry operations.
item: Conference Full-text
Impact of water saturation model on the reservoir estimation ; a case study on dorado and Barracuda Wells in Mannar Basin, Sri Lanka
Wijesuriya, HTTB; Abeysinghe, RYGK; Roshanthan, S; Wickrama, MADMG; Ratnayake, NP; Vijitha, AVP; Senadhira, AMADM; Senevirathne, BSMCK; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, y; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, y
Fluid carrying properties of rocks (permeability) and the interaction between fluid and rock that influence the flow of the fluids(porosity and saturation) are required to evaluate the maximum recovery and producibility of any petroleum reservoir. Determination of Water Saturation (Sw) is a critical and complex petro physical calculation, as there are number of independent methods used to calculate the same. The objective of this research was to analyse the impact of water saturation model on the reservoir estimation, using the well-log data of Dorado-1 well and Barracuda well in Mannar Basin, Sri Lanka. First, quick look analysis was done with the welllog data. Then the saturation of water in pay zones were calculated using five water saturation calculation approaches namely Archie’s equation, Equivalent Model, Indonesia model, Dual Water Model and Juhasz model. For both wells the highest water saturation values were found with Dual Water Model and Juhanz model, 0.89 for the Dorado well and 0.83 for Barracuda well. While Equivalent model gave the lowest saturation value, 0.46, for Dorado well and the Archie’s model estimated the lowest value of 0.60 for Barracuda well. Except the results of Dual Water Model and Juhasz model, all other models estimated different values for water saturation. This leads to a considerable difference in reservoir estimation. Therefore, for a reservoir it is important to establish the most suitable water saturation calculation method to estimate the volume of reservoir correctly.
item: Conference-Abstract
Pore-pressure and fracture pressure gradient prediction model for few exploration blocks in mannar and cauvery basins, Sri Lanka
Jayasinghe, JMSTW; Kurukulasuriya, AC; Jayasinghe, WMTU; Wickrama, MADMG; Senadhira, AMADM; Ratnayake, NP
Wellbore instability, kick and loss of circulation through fractures are the most significant problems observed during petroleum drilling. Selection of an appropriate mud weight is the key solution for these problems. To select a safe range of mud weights, the knowledge of formation pore pressure and fracture gradient of the drilling area is essential. This paper aims to find the most suitable fracture pressure gradient and pore-pressure models for Mannar and Cauvery basins in Sri Lanka. Three pore-pressure prediction strategies, namely, Hottman and Johnson ,1965 [4] method, Ben Eaton ,1975 [9]method and D-exponent method-Eaton ,1975 [9]and three fracture pressure gradient prediction methods, namely, Hubbert and Willis ,1957 [10] method, Matthews and Kelly (1967) method and Ben Eaton (1969 [6] method, were used in this research. Petro-physical data of four wells previously drilled in the Mannar basin and Cauvery basin in Sri Lanka were used to predict pore pressure and fracture pressure gradient using above methods. Then the predicted values were compared with the actual pressure values obtained from well log records of same wells. Area specific variables, including Poisson ratio and Matrix Stress Coefficient were determined prior to the fracture pressure gradient prediction. After determining the suitable prediction methods, a basin analysis software (Petrel), (Schlumberger, 2010.1) software was used to visually interpret and analyse the results. The results of the Pore-pressure analysis suggested that a combination of Hottman and Johnson method and D-exponent-Eaton method are suitable pore pressure prediction models for the study area. The analysis of fracture pressure gradient strategies found that the Ben Eaton method is the most suitable method to predict the fracture pressure gradient of the area.
item: Conference-Full-text
Tunnel design for fractured rocks and suitable support selection
(Department of Earth Resources Engineering, 2008-05) Senthilkumar, M; Senadhira, AMADM; Giriwaksan, S; Welideniya, HS; Dharmaratne, PGR; Karunaratne, S
This research focused on design of a tunnel in highly fractured rocks, and to propose suitable support classes, based on the study carried out at the Upper Kotmale Hydro Power project location. The necessity arises in order to cope up the unpredictable changes in geological patterns which highly influence the continuity of tunnel works. Present tunnelling method in fractured rocks need to be further evaluated to suit the engineering geological patterns and rock types of the area. The rock strength and the fracture intensity are assessed through field and laboratory works, including tunnel mapping and joint intensity surveys. The suitable support class selected based on Q-value system formulated by Nick Barton (Norway) in mid 70's.The data and the borehole samples obtained from site location facilitated to propose a proper support design, suitable to Sri Lankan geotechnical conditions. The variation in the rock mass from unweathered to highly weathered, sound to heavily fractured along a tunnel was accounted in selecting a suitable supporting method to avoid disastrous consequences and to provide a secure working environment. The results of the study were used to develop a model for tunnel design, and to propose modifications to the existing support classes in fractured rocks at Upper Kotmale Hydro Power Project. And it was understood Q-value evaluation could be more suitable than RMR, for Sri Lankan terrain.