Solid Expandable Tubulars Provide Substantial Value to Existing Wells

The potential coupling of two leading-edge technologies has garnered much attention for its substantial business case regarding field development optimization. This specific application consists of marrying single-diameter technology and extended reach drilling (ERD). Using these two technologies as companion pieces in a drilling design can positively impact capital cost structure, resulting in economically superior alternative development scenarios. Single-diameter technology, a natural derivative of the conventional solid expandable tubular system, provides the foundation for a significant increase in the lateral reach of many extended-reach wellbores. This extended lateral reach results in increased reservoir contact that can lead to increased production per well. Increased lateral reach and production per well can ultimately reduce the required field well counts and infrastructure, resulting in improved field development economics. This paper will describe how combining these technologies mitigates critical factors that limit achievable reach including dogleg severity, casing openhole size vs. drillstring size, and ultimately torque and drag. Using solid expandable tubular single-diameter technology with significant friction reduction could extend the current ERD envelope 25 to 100%. More efficient reserves access, economic benefits and technical advantages will also be presented. In conclusion, this paper will discuss the technology's proven, simulated and engineered potential and how it can put more reserves within reach. Introduction Solid expandable tubulars have rapidly evolved over the last few years into a proven openhole drilling liner and cased-hole remedial liner alternative to conventional technology. These systems improve capital efficiency, reduce drilling trouble time, improve field development economics and extend lateral drilling reach, and/or perform extensive remedial work while preserving the required completion and/or completion size. The use of expandable technology has proven to be highly effective as a contingency and a planned well design application. The single-diameter system offers a truly enabling technology to complement the reliable and cost-effective solid expandable tubular applications. As part of the front-end engineering and design for a major North Sea operator, a well design feasibility study was conducted over an existing and planned field development. This study was conducted to assess the relative merits of applying conventional drilling technology versus expandable tubular technology regarding lateral reach and the impact on capital efficiency and potential field development. This welldesignmodeling study indicated potential lateral reachincreases of 25 to 100% with significantly reduced drilling trouble in both fields. Complementary drilling performance and cost studies have also indicated that existing and planned operator well costs and times in the same two North Sea fields can be reduced by over $40MM, or 30 to 50% of the current and forecast drilling cost and time, with the application of solid expandable tubulars and/or single-diameter technology. These well design studies also indicated preservation of desired completion size, which led the operator to conclude that planned subsea templates and associated infrastructure and/or satellite tie-ins can be eliminated from their field developments with solid expandable tubulars and/or singlediameter technology.

From inception, solid expandable tubular technology has been touted as a game-changing technology. The logical end result of the technology, a single-diameter well, consists of a casing string with the same diameter at the top of the well as at total depth (TD). However, many drilling operators were reluctant to embrace even the basic solid expandable tubular concept without any track record, coupled with what they saw as the inherent risks. Now, after five years of commercial installations, solid expandable tubular technology has proven to be a viable and economically feasible alternative to conventional drilling technology. In the majority of these installations, solid expandable tubulars have been deployed as a contingency to save a well when conventional technology failed. While this type of application is appropriate, operators do not reap the full advantage of all the benefits solid expandable tubular technology offers when integrated as part of the well plan. A crucial step in the acceptance of expandable tubulars as a viable well construction method is to plan the system into the initial well design. In order for the tubulars to be planned into the original well design, operators must understand the compelling economic business cases for the application as well as accept the level of risk. The proven track record has helped mitigate the risk level for many operators, who are now focusing on the value proposition this technology provides. Operators must be comfortable with solid expandable technology in order to make the necessary leap of faith to the single-diameter well. This paper will present the progress of monobore technology up to the present. It will discuss the stages achieved and those that still must be overcome to make this technology feasible. The paper will demonstrate that with solid expandable tubular and monobore technology, operators in general and deepwater operators in particular, will be able to maximize reservoir potential and lower drilling costs when using this value-added technology.

Study of the effect of the expansion cone on the expansion process in solid expandable tubulars with thread joints

Historically, operators used solid expandable tubulars as contingencies to mitigate unexpected hole problems, minimize loss of hole size and to meet project objectives. However, some operators quickly realized that by incorporating this technology into their initial field development and workover plans, previously untapped reserves could be brought online. An operator in India combined solid expandable tubulars with sidetracking operations to reach additional reserves with optimized hole size in several offshore wells. Sidetracking out of a milled window results in loss of hole size with consecutive casing strings bringing further reductions. In this common scenario, the operator could be faced with drilling the drain hole with slimhole tools that drastically reduce the flow area and limit logging and drilling equipment availability. Planning the application of solid expandables through the milled window in these vertical wells allowed the operator to economically extract previously unswept reserves. With conventional technology they were faced with exiting out of the 9-5/8 in. casing and setting 7 in. and 4-1/2 in. liners to isolate problematic and depleted zones above the pay zone. The pay zone would be drilled using 3-3/4 in. slimhole tool strings that placed restrictions in the outflow of the reservoir and compromised the workover program economics. This paper will discuss how the planned-in use of expandable tubulars enabled the operator to sidetrack and recomplete poor-producing vertical wells into horizontal wellbores. This approach allowed the operator to maintain optimum drain hole that resulted in a five-fold increase in daily oil production. The paper will describe the complimentary technologies used with the solid expandables and the lessons learned in the first two wells. The operator/contractor relationship will also be discussed regarding project management of multi-well workover programs for both offshore and onshore fields.

New and innovative technology has a way of significantly influencing peripheral products and processes. A case-in-point is the relationship between solid expandable tubulars and cementing practices. The early years of cementing expandable casing were filled with researchers working to develop novel chemistries and resourceful techniques for annular sealants that varied from modified conventional cements to highly-specialized non-Portland systems such as resins. Experience and time relegated many of these chemistries and systems to specific situations. Instead of needing atypical techniques and unique products, the more effective and applicable approach with solid expandables consisted of modified placement practices, training, logistics, and refined engineering of conventional cementing methods. But, as solid expandable tubulars are installed in deeper and higher-angled wells, annular sealant methods and products will be required to function in more extreme conditions. This paper will examine the evolution of cementing processes and products for solid expandable tubulars. Emphasis is placed on best practices and lessons learned, with the intent of giving the reader a practical field guide. Checklists for key slurry design issues and how they correlate with the job logistics of the expansion operation will be included. This paper will also discuss foreseeable application trends in expandable use and logical modifications and enhancements in cementing procedures, technology and chemistries.

As an enabling technology, solid expandable tubulars continue to revolutionize the design and construction of oil and gas wells. Although solid expandable systems are now widely accepted as a viable casing alternative, some operators do not apply the technology in their wells. Limited information regarding the tubulars' post-expansion performance properties creates uncertainty in the application of solid expandable tubulars. A better understanding of how the pipe properties are affected by the expansion process is imperative to optimizing the benefits of system application. Using American Petroleum Institute (API) performance equations on post-expanded tubulars do not clearly identify the limits of the pipe. Testing is underway to create accurate predictive models for expansion force and post-expansion collapse. These full-scale laboratory tests, using API methods where applicable, determine how the expansion process changes collapse resistance and residual stress. Pre and post expansion mechanical and material properties are analyzed using American Society for Testing and Materials (ASTM) methods. Testing for H2S and CO2 environments employ the NACE methods. This paper describes the testing procedures and results of the post-expansion performance property testing. These findings will be compared and contrasted to API standards for conventional pipe. In addition, the paper will discuss industry implications for determining solid expandable tubular standards.

Many modern well construction techniques have been developed with an eye toward drilling deeper, longer, and more cost effective Extended Reach Drilling (ERD) wells. One notable technology that has contributed to this effort is solid expandable tubulars. This technology was developed specifically to allow additional casing strings to be run to cover up problem zones and facilitate drilling the well to the ERD target. Solid expanable tubulars also help to reduce the overall resources required to construct the well. Projections show that using them would significantly reduce the size or volume, as well as the cost of the rig, the drill string, the bits, the cement, and, of course, the casing, resulting in lower overall costs. This result has been born out in practice and will culminate in the single-diameter well described elsewhere.1 The effects on ERD wells will be substantial, but there are important ‘side effects’ that can have a profound cumulative effect. The torque and drag on an ERD well is usually the limiting factor in the actual reach possible. These limits are mitigated by drilling fluid properties and the use of rotary steerable drilling tools among other technologies. Torque and drag are primarily influenced by geometric conditions like dogleg severity (DLS) and casing open hole size vs. drill string size, surface effects (commonly grouped together and named the friction factor), and drill string dynamic conditions (such as axial and rotary motion that overcomes the friction). The use of solid expandables has two distinct effects that can be favorable for the drilling of ERD wells. An important effect is that more favorable drill string casing geometry is possible and can reduce the tendency for helical buckling or drill string lockup. Another important impact is the ability to use larger drilling tubulars. This paper will examine data supporting the positive effect of solid expandable tubulars on drill string torque and drag. Data modeled for an ERD well shows the theoretical drilling limit improvement from these effects in real example wells. Extended reach drilling limitations have been pushed out significantly in recent times. Advances in mud systems, geomechanics, and the advent of rotary steerable systems have significantly improved the ability to reach further to access hydrocarbons. However, limitations, though receding, still exist. To counter them, new approaches are being developed that attack in various ways the traditional boundaries of extended reach drilling applications.

This article, written by Technology Editor Dennis Denney, contains highlights of paper SPE 87209, "Breakthroughs Using Solid Expandable Tubulars to Construct Extended-Reach Wells," by Karl Demong, SPE, Halliburton Energy Services; Mark Rivenbark, SPE, Enventure Global Technology; and David Mason, SPE, Shell Technology Ventures, prepared for the 2004 IADC/SPE Drilling Conference, Dallas, 2-4 March.