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Abstract Distributed Fiber Optics (DFO) technology has been the new face for unconventional well diagnostics. This technology focuses on measuring Distributed Acoustic Sensing (DAS) and Distrusted Temperature Sensing (DTS) to give an in-depth understanding of well productivity pre and post stimulation. Many different completion design strategies, both on surface and downhole, are used to obtain the best fracture network outcome; however, with complex geological features, different fracture designs, and fracture driven interactions (FDIs) effecting nearby wells, it is difficult to grasp a full understanding on completion design performance for each well. Validating completion designs and improving on the learnings found in each data set should be the foundation in developing each field. Capturing a data set with strong evidence of what works and what doesn't, can help the operator make better engineering decisions to make more efficient wells as well as help gauge the spacing between each well. The focus of this paper will be on a few case studies in the Bakken which vividly show how infill wells greatly interfered with production output. A DFO deployed with a 0.6" OD, 23,000-foot-long carbon fiber rod to acquire DAS and DTS for post frac flow, completion, and interference evaluation. This paper will dive into the DFO measurements taken post frac to further explain what effects are seen on completion designs caused by interferences with infill wells; the learnings taken from the DFO post frac were applied to further escalate the understanding and awareness of how infill wells will preform on future pad sites. A showcase of three separate data sets from the Bakken will identify how effective DFO technology can be in evaluating and making informed decisions on future frac completions. In this paper we will also show and discuss how DFO can measure real time FDI events and what measures can be taken to lessen the impact on negative interference caused by infill wells.
Abstract Current drilling practice allows the drilling of wells whose horizontal drain sections maximise reservoir contact by remaining within a single productive zone. The well path may include sharp azimuth changes, which increases friction drag along the wellbore and precludes access and egress by conventional intervention techniques. This paper aims to demonstrate that a low weight, low friction and high strength carbon composite rod can reach the toe of even the most challenging profile of well. A carbon composite rod of small diameter and containing an embedded electrical conductor is used in combination with standard tractors to deploy logging or other intervention tools into challenging wells. In such wells, the limiting factor for well intervention is the friction drag of the deployment system along the wellbore, especially where azimuth changes. The light weight of the rod combined with its extremely low friction coefficient means that drag is reduced to a minimum allowing access to TD while also ensuring safe retrieval without exceeding safe working load. The carbon composite rod system has been used on a number of interventions that provide proof of concept for combined operations with a tractor in horizontal well systems. In each case the well and BHA was extensively modelled using the proprietary software designed specifically for the carbon composite rod system. In one case the objective was to maximise the payload that could be conveyed rather than the absolute depth achieved. Following extensive modelling including tractor performance, a toolstring measuring 459ft and weighing 7,260lbs was selected and run successfully in a horizontal well. The predicted behaviour compared very favourably to the data recorded during the job, confirming the accuracy of the models. For an extended reach well where the objective is to obtain production and reservoir data all the way to the toe, the relatively small size and weight of the logging tools means that achievable depth is increased. A number of wells with challenging profiles that had never been successfully logged post completion were modelled using the latest software and operational parameters derived from recent experience. In each case, it was predicted that TD could be achieved and that the string could be safely retrieved from the well. Demonstrating the convergence of predicted and actual performance of the carbon composite rod under a number of scenarios gives confidence in the validity of the models incorporated in the simulation software. Using these models to predict the performance in extended reach wells, especially in the cases where there are significant azimuth changes, will allow planning for rigless interventions where access or successful retrieval has been impossible up until now.
Abstract Ballistic perforation remains a fundamental part of the process of producing valuable hydrocarbon deposits. The basic technique of lowering a gun containing shaped charges into a well is essentially unchanged since the 1930's, but the method of deployment has undergone many improvements. This paper intends to examine the benefits and advantages of using new carbon composite materials technology in increasing the efficiency and effectiveness of perforation. The semi-stiff carbon rod is very strong, rigid, has low friction and contains an electrical conductor. These factors all combine to confer significant advantages over wireline for deploying perforation guns. The simplest benefit is that the strength of the rod makes rigging up and running very long and heavy gun strings feasible, reducing the number of runs in hole required to perforate a given interval. The rigidity of the rod reduces the risk of being blown up-hole by pressure differentials, thus allowing more potential underbalance than when using wireline while the conductor allows the use of addressable select fire systems. Economic management of a well will almost certainly involve some intervention during its lifetime. A not uncommon example is a well where depletion has moved reservoir contacts and re-perforation becomes desirable to maximise recovery. If deviation is high, as in a recent well in the North Sea, a tractor intervention will be required and due to the constraints of a conventional cable deployment, gun lengths will be limited resulting in multiple runs. The carbon composite rod system was able to halve the number of runs required to perforate the new interval resulting in a considerable saving. Many wells may not be horizontal but have a sustained section at high angle which precludes the use of wireline alone. The low friction of the rod and the ability to push it into hole allows access without recourse to a tractor, while the stiffness prevents movement of the string uphole after shooting, allowing significant underbalance to be applied with all the attendant benefits to reservoir performance. Combining new developments in selective firing and flexible gun systems with the attributes of the rod allow access to zones below known restrictions which are currently impassable by tractor or any other conventional deployment system. Demonstrating the ability of the carbon composite rod system to save time and perforate longer sections more economically allows optimised planning. Eliminating concerns over gun lift, especially in high deviations, gives far more flexibility for planning underbalance perforation with all its intrinsic advantages. The electrical conductor in the rod enables the use of addressable select fire systems and head tension devices that, along with the ability to push the BHA, allows entry through otherwise impassable restrictions.
Abstract An intervention program in a well may require the use of both electric line and slick line to convey a variety of services. This calls for the swapping between conveyance systems, often multiple times in a single intervention program. A viable solution is a new system for carrying out interventions in oil wells which is designed to convey electrical, electro-mechanical and mechanical services. The paper aims to describe this new conveyance system and discuss field experience to date. Carbon composite material technology confers the benefit of higher strength at reduced weight when compared to conventional cable materials and the slick surface eliminates the need for grease injection pressure control systems. The ability to perform both precision logging and heavy duty mechanical services within the same rig-up allows complex well programs to be executed with only one unit and a multi-skilled crew. The first field trial for the new conveyance system was conducted offshore in the North Sea, and proved the carbon composite rod capable of performing both mechanical intervention (16 runs) and electric line (12 runs) services. The strength of the rod material enables the running of long and heavy bottom hole assemblies. Run in conjunction with electrical or mechanical release devices, the carbon composite rod is able to deploy strings beyond the capability of conventional wirelines. The physical strength and rigidity of the rod, coupled with its light weight, allow efficient planning of intervention programs where mechanical and electric services are combined in a single rig-up. Since the first trial, advances in technique have brought 10km (32,000 ft.) rods to the field enabling intervention access to, and perhaps more importantly retrieval from, extended reach wells. Equally of interest is the ability of the rod to access short lateral sections without resorting to tractor technology, allowing faster and more economical intervention.
Downhole data acquisition by fiber-optic technology, particularly distributed fiber-optic (DFO) sensing, has gained rapid acceptance. Compared with conventional data acquisition, DFO provides a much better understanding of well and reservoir behavior. Reflecting this trend is the increasing number of well completions equipped with permanent fibers. However, many fibers have been installed only above the production packer and thus are unable to monitor the dynamic changes in the reservoir. During the past several years, Ziebel has developed well intervention technologies for obtaining DFO data from wells without permanent fibers, wells in which fiber installations end above the production packer, and wells in which installed fiber systems have failed.