TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractSelecting the components of fluids for reservoir drilling and completion can require extensive laboratory work to determine the most compatible fluid. Well temperatures in excess of 300°F (150°C) create additional challenges, as the additives required to give water-based reservoir drilling fluids the rheological and fluid-loss characteristics needed to successfully drill and complete long horizontal wells degrade at such elevated temperatures. In addition, supplying the necessary additives to a drilling operation in a remote location can be a major logistical burden, leading to a compromise in the fluid formulation.The Belanak field lies off the coast of Indonesia in the Natuna Sea. The reservoir temperature is high (315°F), and the reservoir sections are drilled horizontally, typically between 3,500 and 4,500 ft and often feature particularly tortuous well paths. A low-solids, brine-based reservoir drilling fluid was required because the wells use premium screens for sand control.Six wells were drilled using the sodium formate-based reservoir drilling and completion fluids. The particle size distribution and concentration of the calcium carbonate bridging solids were monitored closely while drilling to ensure that filter cake quality was not compromised. A chelating agent-based breaker was used to break down the filter cake prior to the onset of production.The laboratory work required to optimize the fluids for this project had to take into account not only the requirements for the best fluid technically, but also the effect of the limitations created by working in a remote location. Considerations included minimum loading of calcium carbonate required to deposit a clean, high-quality filter cake and the effect of mixing brine for the reservoir drilling fluid or completion using seawater in case of a shortage of drill water.Fluid testing carried out in the laboratory included drilling performance at temperature, fluid compatibilities, bridging solids optimization, scale inhibition testing, and breaker selection. The fluid selected was based on sodium formatethe first application of a formate-based fluid in Indonesia.
The effectiveness of a permanent abandonment plug is measured by its ability to bridge the wellbore cross section both vertically and horizontally, including all annuli, with a plugging medium which can withstand the rigors of the environment to which it is exposed (Figure 1 – Barrier Requirements). The most common method for placing a plug in cased hole with an uncemented annulus has required section milling of the casing, making a clean out run and underreaming of the open hole prior to placing a balanced cement plug. A new method is presented which creates a permanent abandonment plug through the use of a system which perforates uncemented casing, washes the annular space and then mechanically places the cement across the wellbore cross section in a single run. This paper outlines the design methods, laboratory testing and operational elements that were assessed during the development phase, as well as the results of field trials used to qualify this technique.
TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractSelecting the components of fluids for reservoir drilling and completion can require extensive laboratory work to determine the most compatible fluid. Well temperatures in excess of 300°F (150°C) create additional challenges, as the additives required to give water-based reservoir drilling fluids the rheological and fluid-loss characteristics needed to successfully drill and complete long horizontal wells degrade at such elevated temperatures. In addition, supplying the necessary additives to a drilling operation in a remote location can be a major logistical burden, leading to a compromise in the fluid formulation.The Belanak field lies off the coast of Indonesia in the Natuna Sea. The reservoir temperature is high (315°F), and the reservoir sections are drilled horizontally, typically between 3,500 and 4,500 ft and often feature particularly tortuous well paths. A low-solids, brine-based reservoir drilling fluid was required because the wells use premium screens for sand control.Six wells were drilled using the sodium formate-based reservoir drilling and completion fluids. The particle size distribution and concentration of the calcium carbonate bridging solids were monitored closely while drilling to ensure that filter cake quality was not compromised. A chelating agent-based breaker was used to break down the filter cake prior to the onset of production.The laboratory work required to optimize the fluids for this project had to take into account not only the requirements for the best fluid technically, but also the effect of the limitations created by working in a remote location. Considerations included minimum loading of calcium carbonate required to deposit a clean, high-quality filter cake and the effect of mixing brine for the reservoir drilling fluid or completion using seawater in case of a shortage of drill water.Fluid testing carried out in the laboratory included drilling performance at temperature, fluid compatibilities, bridging solids optimization, scale inhibition testing, and breaker selection. The fluid selected was based on sodium formatethe first application of a formate-based fluid in Indonesia.
A comprehensive and quantitative evaluation of the mud mixing, solids control and waste management systems on rigs prior to the commencement of a drilling operation has been shown to dramatically improve operational efficiency and ultimate fluid-related costs. This paper discusses the evaluation process, which includes an audit of the total fluids system, aimed at assuring that the solids control, fluids handling and mixing systems are functioning to specifications and configured properly for the well objectives. The authors will examine in detail the various components of an intensive rig evaluation, which include everything from the condition and configuration of the shakers to the dimension of the mud pits and their fittingness for treating and processing the specific mud volumes required for a given project. In addition, the evaluation includes a safety audit of all areas where fluid engineers will be working, such as the pit room and shaker house. In demonstrating the effectiveness of such an evaluation, the authors will consider specific examples, including audits conducted on newbuilds, rigs undergoing refurbishment and even to improve the solids control and waste management efficiency of units while a well was in progress. The authors will discuss the results of an evaluation of an entire fleet of deepwater rigs with emphasis on the subsequent recommendations. On one deepwater rig in the Gulf of Mexico, the operator saved $48,000 in fluid-related costs when the evaluation revealed that the solids control equipment was not operating at peak efficiencies. Many existing rigs are found to require only a minimum amount of repair or adjustments to show improvements. On most occasions, the evaluation can be used to construct more efficient solids processing and waste management plans. Introduction Be it a drilling rig or platform, an efficient fluids handling system produces a number of economic and operational advantages.1,2,3,4,5 If operating at peak efficiency and properly configured for the well objectives, the fluid processing arrangement, especially the solids control system, can increase penetration rates, reduce drilling fluid costs, minimize abrasion and wear and lower disposal costs. The environmental benefits of a proficient solids control system is illustrated by a reduction in the total volume of waste generated by the drilling operation. Critical to the effective performance of a total fluids handling network is having equipment that is properly sized, installed and operated as per the objectives of the well. For instance, just as the composition of drilling fluids employed in the deepwater environment differ significantly from those used onshore and in shallower water, the makeup of fluids handling systems likewise vary dramatically with specific well objectives. The application must be considered carefully when selecting and configuring the mud handling, solids control and waste management system. The equipment may be new and functioning superbly, but if not matched up correctly it is of little value. For example, the ability to circulate at high flow rates, thereby increasing penetration rates, can be restrained if the removal of cuttings from the drilling fluid cannot match the circulating rates.2 Furthermore, ever-tightening environmental regulations, especially those concerned with oil-on-cuttings retention, and the economic ramifications of using expensive synthetic-based and other expensive and exotic drilling fluids, mandate a handling system that will optimize fluid recovery. In addition, with total containment and cuttings slurrification becoming more popular, any existing fluid and cuttings handling system must be flexible enough to meet the requirements of those techniques.
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