When emergency situations in environmentally sensitive areas occur, drilling a relief well to intercept and kill the blowout well often requires various types of magnetic ranging technologies to navigate into the problematic well. Outside this scenario, we do not commonly hear about magnetic ranging. The main objective of this paper is to raise awareness among operators about magnetic ranging-while-drilling technology as wellbore placement service to make planned wellbore intersections to boost production. Reactivation of mature fields is often an economically viable option when demand for energy pushes oil prices upwards. In order to boost production from an existing mature field, an operator provided a service company with an interesting challenge: utilize proven directional drilling expertise in conjunction with alternative wellbore positioning techniques to drill two high-angle deviated wells from opposing directions and intercept a common vertical producer well for a gravity drainage concept. During the pre-planning phase, one of the major challenges was MWD survey accuracy for the horizontal wells. The 2-sigma major-axis uncertainty of the MWD surveys after applied corrections at the point of planned contact with the vertical producer was over 106 ft while the size of the target to intercept was only 1 ft in the lateral dimension. Implementation of magnetic ranging while drilling technology combined with north-seeking gyroscopic sensor allowed optimal positioning of all three wells relative to each other. Bottom hole assembly equipped with a smart mud motor, MWD, and magnetic bit-sub avoided collisions and steered successfully between other producing wells in the mature field. This challenging project from two opposite surface locations took several weeks of directional drilling and resulted in precise positioning both horizontal drainage sections within close proximity of vertical producer. Hydraulic communication with the vertical producer was successfully established from both horizontal wells after completion of the drilling operations.

This paper describes how active and passive magnetic ranging logging used while drilling subsurface intervention wells shows characteristics of the target well casing integrity and damage. Over the course of the development of a novel active magnetic ranging system and through several years of commercial application, data has been collected and analyzed to understand the characteristics of casing damage. This paper explains the methods used in field operations to collect this data. Using the gathered information, various stages of casing damage and poor integrity are shown. Results obtained from active and passive magnetic ranging are presented in the context of identifying casing damage. This is a departure from the standard methods of interpreting the data as it is not focused on locating a wellbore but determining the integrity of the casing. Casing integrity in idle wells is usually understood by conventional logging techniques until there is a restriction or damage on the well. Magnetic ranging logging performed during the intervention to abandon these wells can give an indication to operators of the casing integrity that otherwise would have been unknown without access to the damaged well. This can help optimize subsequent abandonment procedures as well as assist with field planning into the future to mitigate issues stemming from casing integrity and to identify the causes of previously unknown critical casing damage. The paper reports surface experimental data and compares it with two field examples. In the first field example, the passive magnetic interference from a hundred-year-old casing in the offset well caused more than 100000nT deviation from the reference field approximately 1ft away from the offset well, suggesting severe casing damage. The active magnetic signature measured simultaneously approaches zero, pointing to a lack of electrical continuity in the offset casing caused by a complete break. The second field example shows an offset well segment with passive interference of 7000nT in the presence of a stable active magnetic signal at approximately 2ft separation between wells due to possible casing damage without complete separation. The passive interference increases to 14000 nT at deeper depth while the active signal approaches zero due to a complete casing break. Novel application using the data collected by active and passive magnetic ranging techniques is being applied for the understanding of issues related to casing integrity.

The field experience in the continental US suggests that approximately 33% of plug and abandonment operations are non-routine, and 5% require re-entry (Greer C.R., 2018). In some scenarios, the most cost-efficient option for the intervention is drilling an intercept well to re-enter the target well or multiple wells externally using advanced survey management and magnetic ranging techniques. This paper presents the methods applied of relief well methodologies from the planning to execution of a complex multiple-well abandonment project. Improvements in Active Magnetic Ranging sensor design and applications have improved the availability of highly precise tools for the purpose of locating and intercepting wellbores where access is not possible. These instruments were commonplace on relief well interventions, however, have found a new application in solving one of the major issues facing the oil and gas industry. Subsurface abandonments are a complex task that requires a robust methodology. In this paper, we describe the techniques that have been built upon the best practices from industry experience (ISCWSA WISC eBook). This paper also illustrates how the combination of advanced survey management, gyro surveying, and magnetic ranging can be used following the best industry practices for fast and cost-efficient non-routine plug and abandonment. Case studies of several abandonment projects are presented showing the various technical challenges which are common on idle and legacy wells. The projects include wells that are currently under the ownership of an operator and orphaned wells that have been insufficiently abandoned and left idle over many decades. The case studies outline how the application of relief well methodologies to the execution of complex sub surface interventions led to the successful outcomes of meeting environmental and government regulations for wellbore abandonment. This includes performing multiple zonal isolations between reservoirs, water zones and preventing oil and gas seepage to the surface. The projects and their outcomes prove economically viable strategies for tackling the growing issue of idle and orphaned wells globally in a fiscally responsible manner. Combining industry best practice methods for relief well drilling, along with the technological advancements in magnetic ranging systems is a solution for one of the largest dilemmas facing the oil and gas industry in relation to idle and orphaned wellbores. These applications allow previously considered impossible abandonments to be completed with a high probability of long-term success in permanent abandonment.

Globally, there are numerous offshore legacy assets, including offshore platforms, subsea infrastructures, and wells that exist, however, are at or approaching their end of life and require decommissioning. Within the range of infrastructure, there is a subset of assets that are categorized as complex to decommission due to being unable to either gain access to the wellbores from the surface with offshore drilling units or there exist casing integrity issues which restrict the ability to access the wellbore. This paper will outline methods that can be applied in the offshore environment to successfully and economically decommission these assets using sub-surface intervention technology. The long-term environmental impacts of not taking action on these assets can be significant, and up until now, the problem has faced economic challenges and high technical risks to remedy. The methods for complex decommissioning are drawn from a history of relief well intervention and onshore complex plug and abandonment. This paper will outline the methodology required to lower the risk of offshore complex decommissioning. The methods presented utilize active and passive magnetic ranging technology with no access to the target wellbore. Experience on land-based operations has proven the methodology for complex decommissioning challenges, which enables wells to be abandoned economically with highly successful outcomes. The process is a permanent remedy to intervene and abandon wellbores mitigating environmental impacts and enabling operators to satisfy the growing change in perception with regards to the environmental obligations of the oil and gas industry. The methods and technology applied for permanent decommissioning of subsurface assets have been optimized for offshore operations. These processes ensure that the economic cost is controlled through the application of risk-based methodologies and a proven, consistent approach to the execution of the operations. The active and passive magnetic ranging systems are undergoing a constant research and development process to further optimize the operations with the novel methods being shown in this paper.

Summary The growing problem of well-to-well fracture interactions in North American shale plays dictates the need for more accurate interlateral spacing measurements. Conventional wellbore surveying techniques, such as magnetic and gyroscopic measurements while drilling (MWD), cannot guarantee optimal placement due to growing systematic errors that dominate survey uncertainty. This uncertainty may impede optimal field stimulation modeling because the wellbore positioning data used in the analytical calculations are inaccurate. Multiple industry technical papers demonstrate a correlation between interlateral spacing and the severity of frac hits. The interlateral distance measurements are used in the calculations for optimal reservoir stimulation and frac hit modeling. With present commodity prices, the industry cannot afford suboptimal field development caused by inaccurate well placement. In this paper, we compare the conventional survey technique with a commercially proven long-distance active magnetic ranging system that supplements the traditional MWD system. We apply relevant survey error models to two exemplary well pads—an actual well pad from a West Texas shale play and a realistic, although hypothetical, example—and compare them with relative ranging uncertainty. The first example shows that MWD positional error exceeds relative ranging uncertainty while the wells are still near vertical at approximately 6,500 ft measured depth (MD). The second example shows that interlateral spacing uncertainty using active magnetic ranging can be 50% of the MWD semimajor error at the end of the curve at 10,000 ft MD [8,910 ft true vertical depth (TVD)] before the lateral section starts. The MWD uncertainty then gets larger due to systematic survey errors multiplied in the “dead reckoning” computation process. With the magnetic ranging applied while drilling, the ranging uncertainty stays practically the same throughout the whole well, enabling tenfold improvement in interlateral spacing accuracy.