ENVIRONMENTAL ASSESSMENT OF SYNTHETIC-BASED DRILLING MUD DISCHARGES TO BASS STRAIT, AUSTRALIA

1998 ◽  
Vol 38 (1) ◽  
pp. 610
Author(s):  
G.W. Terrens ◽  
D. Gwyther ◽  
M.J. Keough

Esso Australia Ltd. (Esso) on behalf of the Esso/BHP joint venture undertakes exploration and development drilling activities to produce oil and gas from the Gippsland Basin in eastern Bass Strait. As part of the environmental management of the operation, a field monitoring program was undertaken to verify the predicted limited effect on the seabed of the discharge of residual synthetic based mud (SBM) adhered to drill cuttings.Reservoir studies of the mature Fortescue oil field identified scope to more efficiently deplete existing reserves as well as develop undrained oil pools within the known reservoir system. As such, 18 additional wells were drilled from the Fortescue platform in 1994-1996 following the original development drilling program when 21 wells were drilled in 1983-1985.Esso's standard drilling fluid in Bass Strait is an environmentally acceptable water based mud (WBM). However, due to the high frictional forces involved the greater lubricating properties of a non-water based drilling mud were required to drill the long reach, high angle sections of seven of the additional wells. The ester SBM was chosen on the basis of its lubricity and biodegradability, to reduce any potential environmental effects from the persistence of non-water based mud in seabed sediments.A seabed monitoring program was undertaken around the Fortescue platform by taking seabed samples from August 1995 to August 1997 at sites along a transect following the predominant ocean current and at control sites, before, during and after the period in which SBM cuttings were discharged. The seabed sediments were measured for esters, barium, biological changes and grain size. Results show clearly the increase in esters concentration in sediments during drilling, then the rapid decrease after completion of cuttings discharge. After a recovery period of 11 months from completion of SBM drilling, SBM esters were not detected in sediments. Sediment barium concentration was also found to be elevated, but only after SBM had been used, indicating greater dispersion of WBM than the more cohesive SBM. The barium concentrations found generally do not have measurable effects on biota. The impact on the sediment biology was found to be limited to the sampling site 100 m from the platform discharge point with recovery evident within four months of completion of drilling.Mechanisms for recovery of the minimal zone of effect are thought to be a combination of the biodegradation of the ester SBM used and the physical seabed dispersion process evident in eastern Bass Strait generated by the continuous series of storms which pass through especially in winter.

2021 ◽  
Vol 1 (2) ◽  
Author(s):  
Osei H

High demand for oil and gas has led to exploration of more petroleum resources even at remote areas. The petroleum resources are found in deeper subsurface formations and drilling into such formations requires a well-designed drilling mud with suitable rheological properties in order to avoid or reduce associated drilling problems. This is because rheological properties of drilling muds have considerable effect on the drilling operation and cleaning of the wellbore. Mud engineers therefore use mud additives to influence the properties and functions of the drilling fluid to obtain the desired drilling mud properties especially rheological properties. This study investigated and compared the impact of barite and hematite as weighting agents for water-based drilling muds and their influence on the rheology. Water-based muds of different concentrations of weighting agents (5%, 10%, 15% and 20% of the total weight of the drilling mud) were prepared and their rheological properties determined at an ambient temperature of 24ᵒC to check their impact on drilling operation. The results found hematite to produce higher mud density, plastic viscosity, gel strength and yield point when compared to barite at the same weighting concentrations. The higher performance of the hematite-based muds might be attributed to it having higher specific gravity, better particle distribution and lower particle attrition rate and more importantly being free from contaminants. The water-based muds with hematite will therefore be more promising drilling muds with higher drilling and hole cleaning efficiency than those having barite.


2018 ◽  
Vol 8 (8) ◽  
pp. 1386 ◽  
Author(s):  
Hazlina Husin ◽  
Khaled Abdalla Elraies ◽  
Hyoung Jin Choi ◽  
Zachary Aman

Water-based mud is known as an environmental-friendly drilling fluid system. The formulation of water-based mud is designed to have specific rheological properties under specific oil field conditions. In this study, graphene nanoplatelet and silver nanoparticle (nanosilver) were added to a water-based mud formulation in which they act as drilling mud additives. Rheological properties measurements and filtration tests were conducted for evaluating the influence of the added nanoparticles. The results showed that the graphene nanoplatelet and the nanosilver increased the plastic viscosity (PV) by up to 89.2% and 64.2%, respectively. Meanwhile, both the yield point (YP) and the fluid loss values were reduced. In addition, we believe this is the first result ever report where nanosilver is utilized for enhancing-enhanced water-based mud’s performance.


2020 ◽  
pp. 70-74
Author(s):  
V.V. Guliyev ◽  
◽  
◽  

Currently, a great number of drilling fluids with different additives are used all over the world. Such additives are applied to control the properties of the drilling mud. The main purpose for controlling is to achieve more effective and safe drilling process. This research work aims to develop Water-Based Mud (WBM) with a Coefficient of Friction (CoF) as low as Oil-Based Mud (OBM) and better rheological properties. As it is known, produced CoF by WBM is higher than OBM, which means high friction between wellbore or casing and drill string. It was the reason for studying the effect of nanosilica on drilling fluid properties such as lubricity, rheological parameters and filtrate loss volume of drilling mud. The procedures were carried out following API RP 13B and API 13I standards. Five concentrations of nanosilica were selected to be tested. According to the results obtained, it was defined that adding nanosilica into the mud decreases CoF of basic WBM by 26 % and justifies nanosilica as a good lubricating agent for drilling fluid. The decreasing trend in coefficient of friction and plastic viscosity for nanosilica was obtained until the concentration of 0.1 %. This reduction is due to the shear thinning or pseudoplastic fluid behavior. After 0.1 %, an increase at PV value trend indicates that it does not follow shear thinning behavior and after reaching a certain amount of dissolved solids in the mud, it acts like normal drilling fluid. The yield point of the mud containing nanoparticles was higher than the basic one. Moreover, a growth in the concentration leads to an increase in yield point value. The improvement of this fluid system cleaning capacity via hydraulics modification and wellhole stability by filter cake endurance increase by adding nanosilica is shown as well. The average well construction data of “Neft Dashlary” field was used for the simulation studies conducted for the investigation of hydraulics parameters of reviewed fluids for all series of experiments. The test results were accepted reliable in case of at least 3 times repeatability.


Author(s):  
Bunyami Shafie ◽  
Lee Huei Hong ◽  
Phene Neoh Pei Nee ◽  
Fatin Hana Naning ◽  
Tze Jin Wong ◽  
...  

Drilling mud is a dense, viscous fluid mixture used in oil and gas drilling operations to bring rock cuttings to the earth's surface from the boreholes as well as to lubricate and cool the drill bit. Water-based mud is commonly used due to its relatively inexpensive and easy to dispose of. However, several components and additives in the muds become increasingly cautious and restricted. Starch was introduced as a safe and biodegradable additive into the water-based drilling fluid, in line with an environmental health concern. In this study, the suitability of four local rice flours and their heat moistures derivatives to be incorporated in the formulation of water-based drilling fluid was investigated. They were selected due to their natural amylose contents (waxy, low, intermediate, and high). They were also heat moisture treated to increase their amylose contents. Results showed that the addition of the rice flours into water-based mud significantly reduced the density, viscosity, and filtrate volume. However, the gel strength of the mud was increased. The rice flours, either native or heat moisture treated, could serve as additives to provide a variety of low cost and environmentally friendly drilling fluids to be incorporated and fitted into different drilling activity.


2013 ◽  
Vol 53 (2) ◽  
pp. 480
Author(s):  
Andrew Smith

The Gorgon Project will develop the Gorgon and Jansz-Io gas fields, located in the Greater Gorgon area, about 130 km off the northwest coast of WA. It includes the construction of a 15 million tonne per annum (mtpa) LNG plant on Barrow Island and a domestic gas plant with the capacity to provide 300 terajoules per day to supply gas to WA. Barrow Island—where Gorgon will be located—is an internationally significant nature reserve and the site of Australia’s largest onshore operating oil field for the past 45 years. As a world-class example of environmental management, it has shown that conservation and development can successfully co-exist. Recognising the importance of Barrow Island’s conservation values, the terrestrial and subterranean environmental monitoring program encompasses key ecological elements on Barrow Island including birds, mammals, subterranean fauna, vegetation, and surface water and land forms. These elements are monitored in relation to the potential impact from environmental stressors identified during pre-construction environmental impact assessments. Here, the author describes the monitoring surveys conducted during the year as appropriate according to the element being considered. All surveys are executed using the Gorgon Project field mobilisation and deployment process, a stringent and dedicated system that ensures all essential health and safety processes are in place and adhered to. Each element is monitored for signs of positive or negative impact across Barrow Island with comparisons made between the pre-determined Terrestrial Disturbance Footprint (TDF) and areas outside of the TDF in which the Gorgon Project is committed to causing zero environmental harm. Statistical control charts and tiered response triggers based on standard deviations are used to inform management decisions about potential environmental effects attributable to the Gorgon Project. A continuous review process is in place to ensure all monitoring programs are scientifically robust and use up-to-date methodologies. Monitoring reports are used to assess the validity of each program and supplementary programs aimed at addressing gaps in existing knowledge are started as and when needed. A reporting framework is in place to ensure regulatory authorities are informed and collaborations are sought to advance overall understanding of the ecology and biology of Barrow Island fauna and flora. The Gorgon Project is operated by an Australian subsidiary of Chevron and is a joint venture of the Australian subsidiaries of Chevron (about 47%), ExxonMobil (25%), Shell (25%), Osaka Gas (1.25%), Tokyo Gas (1%) and Chubu Electric Power (0.417%).


2011 ◽  
Vol 402 ◽  
pp. 709-714 ◽  
Author(s):  
Pei Yang ◽  
Mian Chen ◽  
Yan Jin ◽  
Bing Hou ◽  
Kang Qiu ◽  
...  

The Jabung oilfield in Indonesia is characterized by complex geological structural movement, large tectonic stress and high temperature gradient. Accidents such as borehole collapse and sticking were frequently encountered when drilling shale formations, which often result in serious damage. In this paper, a series of experiments were conducted to evaluate the performance of shale in drilling fluid, including linear expansion rate evaluation tests and rolling recovery evaluation tests. Also X-ray diffraction was used to analyze the mineral composition of shale. The mechanical parameters of shale were obtained through statistical analysis. By using ABAQUS software, the temperature difference induced by thermal stress distribution was analyzed. After that, the borehole stress distribution was determined by coupling the additional stress with in-situ stress. Finally, based on borehole stability mechanical models, the effects of well trajectory on borehole stability were analyzed. We found that the chemical properties of drilling fluid, wellbore trajectory and temperature has a great influence on wellbore stability, and the impact of temperature changes and of well trajectory are the largest factor.


2012 ◽  
Vol 151 ◽  
pp. 319-322 ◽  
Author(s):  
Fang Fang Wei ◽  
Yi He Zhang ◽  
Feng Zhu Lv

In this paper, sulfonates based on the enriched organic compounds in TNT red water have been prepared and their efficacy in water based drilling mud has been evaluated. The experimental results showed that the sulfonated products can be used as viscosifier for drilling fluid, which suggesting an attractive method for the possible commercial usage of waste red water.


1986 ◽  
Vol 86 ◽  
Author(s):  
George M. Deeley ◽  
Larry W. Canter ◽  
Joakim G. Laguros

Water based drilling muds typically contain clays, barite, lime, caustic soda and other chemicals, such as polymers. Land disposal of these wastes raises the possibility of groundwater pollution which can be abated if the waste is stabilized either by chemical reaction or by solidification through some form of cementation. Many ASTM high-calcium (Class C) fly ashes are cementitious and thus may be useful in stabilization of drilling mud. The basic idea is to stabilize the clay-containing muds using the model of soil and roadbed stabilization with high-calcium fly ash [1]. Fly ash that is not utilized is considered to be a solid waste, so this application would would actually constitute codisposal of two wastes.


2019 ◽  
Vol 2 (2) ◽  

Due to significant variations of the subsurface geology from the surface to the top of reservoir and requirement of different fluid characteristics for drilling various hole there is a need to use various mud systems. These may include a simple spud mud for surface hole section, an inhibitive drilling fluid for reactive shale section, a salt water-based mud for salt diapirs and salt formations, and a highly lubricating mud for deviated hole sections with high dogleg severity.To optimize each of these separate and distinct scenarios, there is a need to change the mud system while drilling to overcome the technical challenges associated with these formations and wellbore profiles. The change over from one mud system to another is typically done between casing points while constructing the well to overcome specific drilling challenges associated with next whole section.There is significant time and effort required to clean the mud circulation system adequately before a mud change over in order to avoid any contamination of the new mud system.This is especially true when displacing a waterbased mud by an oil-based mud or an oil-based mud by a water-based mud.If this is not done properly, contamination of the new mud by the old mud could be a source of major problems due to partial or complete loss of functional ability of the new mud system. An adaptable drilling mud system that can easily be transformed from a spud mud system to an inhibitive, or a high lubricating or a salt water mud can provide the industry a versatile fluid system with multiple hole section applications.This removes much of the NPT associated with mud changeover, reduces the mud cost as compared to mixing a totally new mud system and eliminates concerns regarding mud contamination as well as any disposal or recycling cost for the replaced system. This paper describes a volcanic ash-based drilling mud that can be used as a spud mud to drill the surface hole, can easily be converted to an inhibitive mud system to drill reactive shale sections of a borehole, a salt water-based mud to drill the salt sections and also a high lubricating water-based drilling mud to reduce torque and drag problems in deviated and horizontal boreholes. The flexible and easily convertible nature of the base volcanic ash-based drilling mud has potential to reduce total drilling cost significantly as it eliminates a significant portion of non-productive drilling time associated with mud changeover, cleaning of mud circulation system, new mud preparation, incorporation of new mud in the circulation system and displacement of the old mud from the borehole by the new mud, etc.


2021 ◽  
Vol 36 (5) ◽  
pp. 1-12
Author(s):  
Emine Yalman ◽  
Tolga Depci ◽  
Gabriella Federer-Kovacs ◽  
Hani Al Khalaf

This study investigates the possibility of using rice husk ash as an additive to develop an environmentally friendly and low-cost drilling fluid system. The rice husk ash was added as an additive to water-based bentonite drilling fluids at different concentrations ranging from 2 wt% to 15 wt%. Rheological and filtration properties of each drilling fluid developed were measured by using a viscometer and standard low-pressure low-temperature filter press. Subsequently, cutting carrying index, minimum annulus velocity required to clean bottom of the well efficiently, flow behaviour index and permeability of mud cakes of the formulated systems were calculated in order to assess performance of the systems. The results demonstrated that the rheological and properties were improved depending on concentration of rice husk ash introduced. With the introduction of 15 wt% concentration of rice husk ash, while apparent viscosity and yield point increased by 60% and 183%, respectively, thixotropy and plastic viscosity decreased by 29% and 63%, respectively. On the other hand, drilling fluid with 4% wt% content of rice husk ash reduced the fluid loss by 10%. Moreover, results showed that cutting carrying index, minimum annulus velocity required to clean bottom of the well efficiently and flow behaviour index of the enhanced with the exploitation of rice husk ash in the drilling fluid. This study showed that rice husk ash as a promising additive to use in the water-based bentonite drilling fluids when properly implemented, and hence reducing the impact on the environment, and the total cost for drilling.


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