Reservoir developments that rely on long horizontal wells are common practice. Understanding the inflow distribution from a horizontal well is an ongoing challenge for our industry. The effectiveness of reservoir management decisions are greatly improved with an understanding of the flow distribution across the reservoir interval. While technologies have been developed using tractors or coiled tubing to deploy production logging tools into horizontal wells, it requires a well intervention operation, increases risk exposure and is not always successful. This paper reviews a case study from a multi-lateral well in Alaska where a new style of chemical tracers embedded into the completion equipment was used to derive a quantitative estimate of the inflow distribution in a dual horizontal, multi-lateral well. The chemical tracers, which resemble strips of plastic, are designed to release unique chemical fingerprints when contacted by oil. The tracers are then detected in the oil to concentrations as low as 1 part per trillion. In this case study six locations were selected for placement of oil sensitive tracers. During a shut-in period the strips continue to release their unique chemical tracers causing an increased tracer concentration to develop in the oil immediately surrounding the tracer location. Upon start up, these small volumes of oil, containing the higher concentration of tracer, are displaced to the surface. Samples of the produced oil are analyzed to develop a plot of each tracer’s concentration vs produced volume. The arrival of the oil containing the high tracer concentration is related to the inflow distribution. This paper reviews results from a field deployment in a dual lateral well that contained 3 tracer locations in each lateral. The results from this well indicate that one lateral was producing approximately 30% more than the other lateral. Additionally the data indicates the toe of one of the laterals was a major contributor to the total well flow. This insight into the reservoir performance was obtained with no intervention into the well and only minor modifications to the completion design.

Summary Buckling and its effects are topics of economic and technical interest as extended reach drilling (ERD) and horizontal wells become critical to maximizing recoverable reserves, particularly in the continental United States and Alaska. Previous work has resulted in important discoveries about drillstring buckling, but to date, little testing has been performed on actual drillpipe in a controlled manner, particularly in measuring drillstring whirl. As a result, there can be disparities between theoretical predictions of buckling effects vs. actual field results. These disparities can result in unrealistically high friction factors required to bring calculated values close to actual data, or in many cases, operational difficulties can result such as high torque, low rate of penetration (ROP), drillstring failures, inability to maintain directional control, or inability to reach the planned depth. To learn more about drillstring behavior in buckling conditions, a full-scale buckling test fixture was developed to evaluate the effects of buckling on 2⅞-, 3½-, and 4-in. drillpipe while sliding and rotating inside 7-in. casing. The test fixture incorporated a variety of sensors and cameras to characterize torque, drag, vibration, and drillstring deformation under buckling loads. As part of the test program, low-friction nonrotating protectors were also tested to measure performance under buckling conditions. The test results show that drillstring buckling occurs at far lower loads than predicted by current models, possibly caused by minor deformations inherent in real drillpipe. The results also show that for a given amount of torque or drag, protectors increased the available compressive load by 20 to 30% and substantially reduced vibration caused by drillstring whirl. The test results were used to develop a new semiempirical buckling model that predicts contact forces resulting from drill-drag modeling software in which it was compared against actual data from a large number and variety of wells. The results show an ability to more accurately predict torque, drag, and vibration caused by buckling and whirl.

Buckling and its effects are topics of economic and technical interest as ERD and horizontal wells become critical to maximizing recoverable reserves, particularly in the Continental United States and Alaska. Previous work has resulted in important discoveries about drill string buckling, but to date, little testing has been done on actual drill pipe in a controlled manner, particularly in measuring drill string whirl. As a result, there can be disparities between theoretical predictions of buckling effects versus actual field results. These disparities can result in unrealistically high friction factors required to bring calculated values close to actual data, or in many cases, operational difficulties such as high torque, low ROP, drill string failures, inability to maintain directional control, or reach the planned depth can result.To learn more about drill string behavior in buckling conditions, a full-scale buckling test fixture was developed to evaluate the effects of buckling on 2 ⅞-, 3 ½-, and 4-inch drill pipe while sliding and rotating inside 7 inch casing. The test fixture incorporated a variety of sensors and cameras to characterize torque, drag, vibration, and drill string deformation under buckling loads. As part of the test program, low friction non-rotating protectors were also tested to measure performance under buckling conditions.