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Abstract In November 2016 the Deep Exploration Technologies Cooperative Research Centre (DET CRC) launched the RoXplorer, a coiled tubing (CT) drilling rig for greenfields mineral exploration, delivering a platform for low-cost, rapid, safe and environmentally-friendly drilling. The launch represented an important technical milestone in the development of CT drilling for mineral exploration and has been complemented by a series of very successful field trials in the first half of 2017 The paper presents CT technology and its application for mineral exploration drilling. The three key challenges for CT drilling in mineral exploration are coil durability, drilling hard rocks with low weight-on-bit and sample fidelity. Results for mineral exploration CT-drilling field-trials in the consolidated cover rocks of South Australia and the unconsolidated cover rocks of the Murray Basin in Victoria are presented and outline how each of these challenges was overcome. The outcomes confirm the promise of this cheaper regional prospecting approach to mineral exploration drilling. The results of assay samples of the CT drilling cuttings are remarkable; the assay samples from the CT drilling at Port Augusta trial matched those of diamond drill core from an adjacent hole.
- Geology > Mineral (1.00)
- Geology > Rock Type > Igneous Rock (0.48)
- Materials > Metals & Mining (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Oceania > Australia > Victoria > Murray Basin (0.99)
- Oceania > Australia > South Australia > Murray Basin (0.99)
- Oceania > Australia > New South Wales > Murray Basin (0.99)
Abstract Oil and gas wells are drilled with horizontal and multilateral architecture to improve reservoir contact and maximize production. To evaluate the performance of these wells, coiled tubing (CT) and Wireline (WL) conveyance are routinely used. CT inherently have many technical issues such as lock-up. The WL cannot reach the target depth. To address these challenges, the oil industry introduced well tractors that are combined with CT and WL to offer a significant improvement in well accessibility for all types of open- hole horizontal wells by providing extra pulling force to pull CT and WL all the way to target depth. The objective of this article is to evaluate most of the well tractor technology used in logging and stimulation operations. Moreover, the development of a new slim tractor with improved gripping and pulling force with ability to pass through restrictions in electrical submersible pump (ESP) is presented. This study can help identify areas of improvement for tractor capabilities in future operations.
- Asia > Middle East > Saudi Arabia (0.46)
- North America > United States > Texas (0.28)
Abstract The coiled tubing (CT) industry continues to operate in deeper and higher pressure wells and in more challenging environments, thereby extending the operating envelope for the service worldwide. CT operations for cement milling provides a safer, faster, and more economical solution, but achieving the desired results in a high pressure, high temperature (HPHT) offshore environment using corrosive brine as the milling fluid is challenging. This paper describes various challenges and customized remedies for a cement milling operation in an HPHT well with high-density brine, which made milling challenging because of limitations on pumping rates, low viscosity, and fluid corrosiveness. This offshore gas well had a bottomhole static temperature (BHST) of 400 °F and reservoir pressure of 12,000 psi, with a completion of 9-5/8 in. casing from the surface and a 3-1/2-in. liner hanging from 4,606 meter measured depth (mMD). A 1.75-in. outer diameter (OD) CT string was used to accommodate the internal diameter (ID) restriction of the liner. The allowable pumping rate in the 1.75-in. CT was restricted as a result of pipe friction and low viscosity of milling fluid; however, higher annular velocities were needed to lift the cuttings from the wellbore. To overcome this, additional pumping was performed from the annulus of the 9-5/8-in. section. A positive-displacement, metal-on-metal motor was selected over various types of motors. This paper provides details about best practices, including the selection of brine-compatible elastomeric seals, severe corrosion observed on the motorhead assembly (MHA), and redressing of MHA after each run. It also includes details about laboratory tests performed to identify a suitable viscosifier and corrosion inhibitor, as well as the optimum rate of penetration (ROP) and weight on bit (WOB) to avoid large cuttings, surface-fluid handling, and filtering arrangements. Based on precise tool selection, including power section, bearing section, and corrosive-brine-compatible motor seals, as well as design parameters, such as ROP, annular fluid velocity, particle size, and equivalent circulating density (ECD) under the operating envelope, cement milling of 217 m of cement was completed successfully in an overbalanced condition with no health, safety, and environment (HSE) related issues. Selecting the correct milling motor and mill plays a crucial role in any milling job. Several operational challenges, such as excessive corrosion at a minimum MHA ID, pitting on bottomhole assembly (BHA) components and erosion on ball seats, erosion, and degradation of elastomeric seals at a BHST of 400 °F, were observed. These adverse effects were avoided with engineering controls. The methods used, tool selection, and customized design helped the operator to find a solution for milling a cement plug in an HPHT well with zinc bromide (ZnBr2) brine, which resulted in reduced rig time and avoided the side tracking of the well. The lessons learned, methods, and best practices described in this paper can be used in a similar application worldwide, which can help to minimize issues related to service quality and HSE.
- North America > United States > Texas (0.46)
- Asia > India > Andhra Pradesh (0.28)
Abstract This paper describes a recent Directional Coiled Tubing Drilling (DCTD) job that was completed for an independent operator in the Appalachian Basin. The objective was to access target zones identified adjacent to a recently drilled, vertical well using a lateral sidetrack. The target thickness was around 15ft so accurate depth control was critical. It was also considered essential that the entire reservoir section be drilled underbalanced to minimise formation damage. The challenge was to deliver a productive horizontal sidetrack in an effective and cost-efficient manner. The field development strategy required costs to be kept to a minimum, but the use of high-tech equipment was essential to delivering the production improvements. A 3.2 inch DCTD Bottom Hole Assembly (BHA) and a specialised DCTD engineering software package were enabling technologies. A multi-disciplinary approach was adopted to plan and execute the sidetrack. This approach required inputs to the planning process from all stages in delivering the well, which included: 3D seismic, well trajectory planning, drilling engineering, completions. This project was ultimately successful in that a dry hole was re-entered and sidetracked to create a productive well, thereby validating the technology and multi-disciplinary approach of the team. The lessons learned from this operation can be used to optimise the planning of future wells and maximise the value of re-entering marginal wells and fields.
- North America > United States > West Virginia > Appalachian Basin (0.99)
- North America > United States > Virginia > Appalachian Basin (0.99)
- North America > United States > Tennessee > Appalachian Basin (0.99)
- (7 more...)
Abstract This paper investigates the fatigue behavior of Concentric Coiled Tubing (CCT) and specifically the influence of internal and annular pressures on fatigue life and diametral growth rate. This behavior is assessed relative to that of conventional Coiled Tubing (CT) using samples of identical material, with software modelling predictions providing an additional basis for comparison. Samples of 1.25" CT were situated concentrically within samples of 2.375" CT, and both were repeatedly bent and straightened on a standard CT fatigue testing system, with separate pressures in the inner volume and the annular volume between the CT samples. Current SPE literature does not include prior art for any type of concentric coiled tubing fatigue testing or analysis. The testing apparatus used in this study is the industry standard for the assessment of conventional coiled tubing, however this paper presents the world-first experimental study of concentric coiled tubing fatigue. Since the testing focused on the failure of the smaller diameter samples, baseline fatigue tests were only conducted on the smaller, inner coiled tubing samples. These results are cross referenced to current fatigue models. Concentric samples were tested on the same machine and setup parameters, using special fixturing that allowed the internal sample to move axially on one end, with its pressure contained. A matrix of pressure differentials was examined, with various levels of inner and annular pressures. The exterior pressure was atmospheric for all tests. The orientation of the longitudinal Electric Resistance Welding (ERW) seams in both samples was examined in this study. The current approach to monitor CCT fatigue integrity is to use a conventional CT fatigue model, based on the differential pressures caused by the inner CT pressure, annular CCT pressure, and well pressure. While pressure may be monitored accurately, uncertainties exist with regards to the influence of radial stress in the tube wall and factors such as mechanical abrasion between the inner and outer coiled tubing strings, especially due to the presence of internal longitudinal ERW seams. Current models assume perfect concentricity; however, eccentricity varies throughout the string in real-world applications. Results from this study include an empirical derating factor, post mortem failure analysis (including assessment of the influence of ERW seam abrasion), diametral growth analysis, and recommendations for future testing.
Abstract Many of the high-impact operational and safety incidents in wireline operations are the direct result of incorrect selection or inappropriate operation of surface equipment. Examples of such incidents are pulling tensions on the rig-up equipment components above their safe working loads and using winch units incapable of pulling the tensions required to retrieve heavy tool strings in deep or tortuous wells. Current processes and simulation software used to plan wireline operations are focused on the risks and conditions in which the downhole tools and wireline cables selected will operate; they do not include specific assessments of the adequacy of the surface equipment selected and their associated operating practices. In this paper, we show the outcome of implementing a set of surface equipment assessments in a popular wireline forces modeling software suite. The surface equipment covered in this initial implementation include the wireline cable, hoist (winch) unit, wireline drum, chains/slings, sheave wheels, load cells, powered capstans, and rig anchoring points. We also demonstrate the merits of the quantification of the selected hoist unit horse power and torque versus the tension and speed profiles simulated at all depths for the free and stuck tool conditions. The use of processes and forces modeling software, including suitability assessments of the surface equipment and operational choices, is particularly relevant to long and/or tortuous wells. Selection of marginal surface equipment in these types of wells can impose severe operational limitations not identified during the job planning phase and create hazardous conditions that can result in safety incidents and large financial losses.
Abstract The objective of this paper is to clearly outline the basic principles and techniques required to successfully perform well intervention in wells with low-pressure formations, thief zones, and/or depleted reservoirs—specifically, horizontal or highly deviated wells. The paper aims to review the considerations and provide an example of reliable execution in its most basic form, including simplified calculations designed to be used in conjunction with advanced modeling software available in the industry. Coiled-tubing intervention in lateral wells with fluid-loss potential is inherently high risk. The risk of poor solid suspension or loss of fluid circulation results from the inability to avoid fluid loss and causes costly job failures, lost workstrings or equipment, or reduced well production. For land-based operations in the United States, coiled tubing has been reliably and successfully deployed in depleted and low-reservoir-pressure wells that were unable to support a hydrocarbon or water column to surface. These jobs include sand cleanouts, re-fracture preparation cleanouts, and underbalance millouts in extended laterals. Commingled nitrogen and water-based systems were used to reduce hydrostatic pressures exerted on the reservoir and, thereby, allowed for successful continued circulation. The fluid system was adapted to each well intervention to consider formation type, reservoir fluid composition, job requirements, BHA requirements and limitations, chemical compatibility, cutting suspension potential, and foam integrity. When combined with real-time monitoring of, and response to, well conditions, the occurrence of job failure was greatly reduced.
- North America > United States > Texas (0.46)
- North America > United States > California (0.28)
- North America > United States > South Dakota > Williston Basin > Bakken Shale Formation (0.99)
- North America > United States > North Dakota > Williston Basin > Bakken Shale Formation (0.99)
- North America > United States > Montana > Williston Basin > Bakken Shale Formation (0.99)
Abstract The Kuparuk River unit (KRU) on the North Slope of Alaska is a maturing asset providing a variety of well intervention opportunities necessary to maintain production. Because of the high well count, interventions need to be efficient, and the traditional slickline and electrical line model are being challenged. The primary concern is the multiple rig ups and rig downs to complete the scope of work, but there are also local concerns, such as maintaining a workable equipment schedule in a cold-weather region. Another unique feature of the KRU is that many of the wells have scale deposits. Digital slickline (DSL) has been successfully used in the KRU and was highlighted in previous papers (Wiese 2015). The ability to have real-time depth correlation with a casing collar locator (CCL) and optional gamma ray (GR) during slickline runs and completing the traditional electric line services (i.e., packer set, perforating, etc.) is a game changer that dramatically helps improve intervention efficiency. A previous challenge was maintaining real-time communications in areas where there is excess scale buildup. To circumvent this issue, a new protocol was developed using a radio frequency (RF) antenna to provide half duplex communications with a coated slickline. This methodology doesnot require the tool housing to contact the tubular to complete the signal transmission. In 2017, more than 400 digital subscriber line (DSL) runs covering a wide variety of tasks were successfully completed, including removing and replacing gas-lift valves, fishing packers, string shots, perforating, setting packers, and patches. An interesting result of the KRU digital slickline interventions was that approximately 60% of the runs were slickline centric involving jars and 40% were considered e-line replacement services. This trend suggests that a successful product should be able to complete all typical slickline runs to maintain the efficiency advantage.
Swellable Packer Evaluation Using Multi-Detector Pulsed Neutron Logging and Borax
Cedillo, Gerardo (BP Exploration Alaska) | Zett, Adrian (BP Exploration Alaska) | Han, Xiaogang (BP Exploration Alaska) | Elghonimy, Rana (BP Exploration Alaska) | Raeesi, Behrooz (BP Exploration Alaska) | Itter, David (BP Exploration Alaska) | Hecker, Dodie (BP Exploration Alaska) | Landi, Nancy (BP Exploration Alaska)
Abstract Swellable packer evaluation has become a critical component of Greater Prudhoe Bay (GPB) well design, surveillance and diagnostic strategy. Currently in the field there are several wells constructed with cementless completions with over 500 water or oil swellable packers across three different reservoirs. Several early gas or water breakouts have been documented since these types of completions have been deployed and the need for an accurate diagnostic technique to distinguish between a reservoir phenomenon or a completion failure motivated this work. The borax evaluation technique historically has been successfully used in oil fields on the North Slope of Alaska to detect fluid channeling mainly in horizontal cemented and perforated wells. This technique however, was never used to evaluate swellable packers in horizontal cementless completions. Even when the same multi-detector pulsed neutron (MDPN) instrument could be used in real time or memory conveyance to evaluate either one, there are fundamental differences in how these cementless completions are designed and evaluated compared to the cemented and perforated ones. Ignoring those differences could lead to the wrong nuclear attribute selection and incorrect interpretations, diagnostics and remediation strategies. The objective of this paper is to describe the nuclear modelling performed, the wellsite procedures used, the interpretation workflow, and the results of evaluations of these completions.
- North America > United States > Alaska > North Slope Basin > Prudhoe Bay Field > Ivishak Formation (0.99)
- North America > Trinidad and Tobago > Trinidad > North Atlantic Ocean > Columbus Basin (0.99)
Operational Improvements Using a Coiled Tubing Telemetry System for a Complex Milling Operation in Shut-in Conditions
Kubeisinova, A.. (KPO) | Tankiyev, T.. (KPO) | Izbassov, A.. (KPO) | McGachy, D.. (KPO) | Viti, M.. (KPO) | Pitoni, E.. (KPO) | Correa, P.. (Baker Hughes, a GE Company) | Parra, D.. (Baker Hughes, a GE Company) | Craig, S.. (Baker Hughes, a GE Company) | Livescu, S.. (Baker Hughes, a GE Company) | Yeginbayev, A.. (Baker Hughes, a GE Company) | Nadirov, Z.. (Baker Hughes, a GE Company)
Abstract A new horizontal well in Asia was not capable of unassisted flow due to low gas production rates and a wellhead pressure below that required to enter the production gathering system. Two zones were identified at the heel that could increase the gas/oil ratio (GOR). Because these two zones had deviations greater than 80 degrees, coiled tubing (CT) was selected for the perforation and stimulation intervention. In addition, mechanical isolation was required to ensure the stimulation fluids entered only the new zones. Accurate depth control was required for three runs: setting two composite bridge plugs (CBPs); deploying CT-conveyed perforating (TCP) guns for opening two intervals; and milling out the two CBPs without taking returns to surface. All these runs were performed with a 2.875-in. tube wire-enabled CT telemetry (CTT) system. For the first time, a tension, compression and torque (TCT) subassembly was used to improve the milling operation. The CTT system consists of a customized bottomhole assembly (BHA) that instantaneously transmits internal (i.e., inside the BHA) and external (i.e., outside the BHA) pressure and temperature, and casing collar locator (CCL) data to surface through a non-intrusive tube wire installed inside the CT. Monitoring the BHA force and torque data in real time helped improve the motor and mill performance and life because the weight on bit (WOB) could be adjusted to the recommended values. For instance, based on the optimum working ranges for the motor used, the operator decided how and when to modify the working variables to achieve a reliable and efficient milling process. The CTT system alone helped set the first CBP at 5363 m measured depth (MD), set the second CBP at 5281 m MD, and perforate the intervals between 5297 and 5306 m MD and between 5152 and 5164 m MD. In addition, the CTT system with the TCT subassembly was used to mill the two CBPs in shut-in conditions, without any stalls. This created a continuous milling operation, reducing the job time and the working fluid volume compared to similar milling jobs using CTT system alone. Comparing this CBP milling job performance with a previous operation in another well with similar conditions (depth, deviation, etc.) using the CTT system alone reduced the milling time for one CBP by 22%. Although the overall job performance exceeded the operator's expectations, the working parameters used during the CTT system with the TCT sub-assembly job were not constant, leaving a few areas of improvement for the upcoming milling operations. For instance, the constant differential pressure and WOB were not used on every milling pass down. The novelty of using the CTT system and TCT subassembly consists of real-time monitoring of BHA data for positioning two CBPs and opening new intervals exactly at the required depths. In addition, this approach enables removal of two CBPs by adjusting the milling parameters to achieve the optimum working parameters for the motor and mill, providing direct and positive financial impact for the operator.
- Asia (1.00)
- North America > United States > Texas (0.69)