Continuing their leadership in developing consistent, clear, and reliable practices and guidance for international use in reserves reporting, SPE and sister organizations (AAPG, WPC, SPEE, and SEG) issued in November 2011 a new document entitled Guidelines for Application of the Petroleum Resources Management System (AG) to accompany and support PRMS. The AG updates the 2001 document Guidelines for the Evaluation of Petroleum Reserves and Resources, also published by SPE, which was issued prior to adoption of PRMS by three of these major professional organizations. This new document will assist reserves evaluators throughout the world in understanding PRMS and how it should be applied in financial, regulatory, and reporting activities. Two new chapters (on deterministic reserves estimation and on unconventional resources) have been added to the AG; eight others have been updated; and a comprehensive glossary entitled "Reference Terms?? has been added.
The AG is available free to the public (not just to SPE members) on the SPE website. In addition, the SPE Oil and Gas Reserves Committee (OGRC) has begun to conduct Advanced Technology Workshops throughout the world. These workshops are intended to provide opportunities to discuss the AG and to present and discuss regional examples of PRMS applications.
Nanotechnology has been successfully applied to a variety of products including electronic circuitry, material composites, medical and even consumer goods. Other than a few crossovers, the utility of nanotechnology in the oilfield is still a subject
of discussion as well as debate. Noted efforts by universities and consortiums into such areas as nanosensors, nanomarkers or the more esoteric nanobots to provide valuable data regarding the reservoir are of great focus due to their large potential return on investment, but have yet to yield substantive products. By contrast, efforts into drilling applications of nanotechnology such as drilling fluids are less known.
This paper will review recent works on the application of nanotechnology in shale stabilization, high-temperature tolerance and viscosity modification. This paper will also discuss results from projects which utilize graphene (and graphene derivatives), carbon nanotubes (CNT), nanosilica and other nanochemistries to achieve and enhance the performance of drilling fluids in the applications mentioned above. Further discussion will address some of the concerns and pitfalls of
sourcing and using commercial "nano" products as well as review current HS&E perspective on this new area of chemistry for the oilfield.
As wellbores continue to be drilled deeper and farther than ever before, the need for improved drilling fluid systems that optimize fluid performance in harsh and challenging environments is at its highest demand.
Invert emulsion fluids are frequently chosen due to their high performance and low risk in various applications. Invert fluids are a particularly good choice when dealing with extreme environments, such as those with surface temperatures as low as -26C (-15F) or those wells having bottom hole temperatures in excess of 250C (485F). Invert fluids are typically the preferred choice over water-based alternatives in deepwater and extended reach wells because of their inherently better lubricity and improved wellbore stability. The most important component of the invert fluid is the surfactant package, which maintains the solids in an oil-wet state, assists in filtration control, and stabilizes the internal phase of the fluid.
The latest developments in surfactant chemistries designed for invert emulsion fluids has resulted in a significant improvement in the performance of these fluid systems. Newly developed systems allow for simplified engineering due to formulation flexibility across temperature and density, high internal phase ratios with low viscosity, emulsion stability at temperature extremes, and a greener chemical profile. Each of these has a positive effect on drilling economics, environmental compliance, logistics, and health and safety.
This paper will review the new surfactant technologies, describing both their advantages and drawbacks from the standpoints of drilling performance and applicability, showing example data leading to these conclusions. The authors will also review the recent field usage of the surfactants described.
Flat Rheology Invert Drilling Fluid (FRIDF) has been successfully used for deepwater drilling due to its outstanding performance in providing excellent hole cleaning, temperature-independent rheology profile, good barite sag control and good ECD control. The high performance is achieved by using correct combinations of emulsifier, wetting agent, rheology modifiers and supplementary viscosifiers. Because of the multiple products used, the FRIDF can be complex to engineer and manage. An improved and simplified flat rheology system has been developed to aid in the field engineering and ease of
system maintenance without sacrificing fluid performance.
The newly developed flat rheology system utilizes a single emulsifier component to provide dual functions of emulsification and surface wetting. This helps to improve emulsion stability and enhance thermal stability and fluid lubricity. The system can be formulated for deepwater applications with mud weights up to 18.0 lb/gal and temperatures up to 350°F. In addition, the system uses a new rheology modifier that provides a temperature-independent rheology profile for
hole cleaning, barite suspension, ECD management and lost circulation control.
Recent field trials indicated that the new system is easy to maintain and provides good fluid performance in terms of drilling rate, ECD management, lost circulation control and hole cleaning. Even when the system was contaminated with a severe saltwater flow, there were no fluid-related problems before the synthetic/water ratio was restored. The new fluid system exhibited flat rheology profiles and non-progressive gel structures. Hydraulic modeling showed excellent hole cleaning with low ECDs and breaking-circulation pressure. This resulted in a noticeable reduction of lost circulation potential in lost circulation prone areas. The performance of the new flat rheology system (NFRS) also will be compared to the current system to demonstrate some advantages of the new system.
Extended Reach Drilling (ERD) wells drilled nowadays can reach a step-out of 10 km (33,000 ft) and thus present many drilling challenges, including torque and drag, hole cleaning, wellbore stability, equivalent circulating density (ECD) management, lost circulation management, just to name a few. These challenges can severely limit the desired well depth or increase the operation time, particularly in deepwater environment. A new synthetic-based flat rheology drilling fluid (SBM) with new emulsifier and rheology modifier package has been designed for narrow margin ERD wells.
This newly developed flat-rheology SBM utilizes a novel, single emulsifier to simplify fluid formulation, improve emulsion stability, enhance thermal stability, and provide surface wetting and fluid lubricity. This allows the system to be formulated for any ERD applications with mud weights up to 18.0 lb/gal and temperatures up to 350°F. In addition, the system uses a new rheology modifier that provides temperature-independent rheology profile for better hole cleaning, barite suspension, ECD management and lost circulation control.
A recent field trial conducted in deepwater GoM indicated that the new system is easy to handle and provides good fluid performance in terms of drilling rate, ECD management, lost circulation control and hole cleaning. The SBM at one time was severely contaminated due to salt water flow but the fluid held together without any problems. Similar results on drilling performance were observed with another onshore field trial that used a non-synthetic-based fluid.
This article describes the new flat-rheology SBM system with examples showing typical mud formulations, fluid properties, barite sag performance data, field test data and computer hydraulics simulation of ECD impacts.
Limited amount of rheological data generated under extreme high-pressure, high-temperature, (HPHT) conditions (>500°F/30,000 psi) have been published due to lack of suitable viscometer and drilling fluid for such conditions. This paper compares the rheological properties of invert emulsion drilling fluid generated from four types of HPHT viscometers and provides a simple rheological model that can be used to predict the behavior of OBM under extreme-HPHT conditions.
Previously most of the HPHT studies were limited to 20,000 psi and 500°F. Recently more than one extreme-HPHT rheometers have become commercially available, which can measure the rheological properties of drilling fluids at conditions up to 600°F and 40,000 psi. These viscometers have been used to test various invert emulsion drilling fluid samples to the maximum capacity of the equipment. Parts of the data generated from one particular instrument have been compared with data obtained from other rheometers that are operated at lower temperature and pressure.
The data indicated several factors can critically affect the rheology measurements, including drilling fluid chemistry, instrument set up and test schedule. Rheological properties measured by various instruments differed slightly from each other perhaps due to design differences. Temperature and pressure not only affect the rheological properties of the test fluid but may also impact the performance of the critical mechanical parts used for rheology measurement. In addition, HSE experience gained from working with extreme-HPHT instruments is also included in this paper.