The demand for drilling and completing horizontal wells in both conventional and unconventional oil and gas plays has drastically increased in recent years. A growing economic and environmental appetite for ever increasing horizontal lengths continues to apply pressure on drilling and completion technologies. Although well engineering programs have improved and adapted to solve some of these issues, coil tubing reach capabilities can, at times, become the limiting design factor for horizontal wells. To tackle this issue, the industry has developed and adopted the use of downhole friction reduction tools to optimize and extend the range of coil tubing. Using case history from Shell Canada’s Groundbirch shale gas development, this paper will compare and analyse the effectiveness of three different downhole friction reduction tools currently available to industry. While this paper will discuss the use of Tubing Force Analysis (TFA) modeling software to obtain representative values for comparison, the focus of the study is to compare the overall effectiveness of the three friction reduction tools using actual field data.

Coiled Tubing (CT) intervention operations in extended reach wells (more than 10,000 ft in the lateral length) have become quite common in North America. In general, a 2.0″ CT has enough weight to reach the target depth in a 5,000 ft lateral. Therefore, to reach a 10,000 ft lateral, the use of metal-to-metal friction reducer (MFR) or lubricants will be required to work in conjunction with downhole extended reach tools. However, in some interventions, only lubricants can be used, without the downhole extended reach tool. Various lubricants are available in the CT industry. Based on field operations, a typical lubricant could reduce the coefficient of friction (CoF) by about 20%, while a high performance lubricant could reduce the CoF by up to 50%. In order to reach the bottom of a long lateral well, it is imperative that coiled tubing operators are using the most optimal lubricant in correct applications. In this paper, a linear friction apparatus was introduced and used to evaluate the friction reduction performance of 7 lubricants at various concentrations. With a test fixture, both the static and dynamic CoFs were measured. In addition, the performance of the lubricants was also evaluated with the introduction of polyacrylamide (a fluid friction reducer, FR), the salinity, and sand in the fluid system. The test results indicated that only a few lubricants could effectively deliver CT extended reach. In general, the static CoF of the lubricants was 10% to 30% higher than the dynamic friction. An increase in water salinity and the presence of sand in the wellbore had a negative effect on the performance of the lubricant. A higher lubricant concentration resulted in a lower friction coefficient, especially for the high salinity and sand conditions. However, the use of a fluid friction reducer could be detrimental to the lubricant friction performance when the FR concentration is more than 1%.

In the last decade, the number of horizontal wells drilled in North America has risen dramatically. As a result, there has been an associated increase in the use of the plug and perforation system and the ball-drop system used to complete these horizontal wells. After the fracturing treatment has been completed, the bridge plugs or ball seats are subsequently milled out via the use of coiled tubing (CT). During the plug or ball-seat milling phase, it is difficult to control weight-on-bit at the end of the CT. If the injector releases too much weight at surface, then the weight-on-bit is too high and the downhole motor can experience a stall. Alternatively, if the injector is not releasing enough weight at surface, then there is insufficient weight-on-bit to mill out the plug or ball-seat. Given that these operations are performed in horizontal wells, it is difficult to predict the optimal weight-on-bit without the presence of real-time downhole measurements. The current data acquisition software used on CT field operations does not analyze or interpret the data - - it only records the measurements. As a result, it is an arduous process to identify trends in pressure, depth or CT string weight changes over an extended period of time. However, analyzing changes in these variables is critical for optimizing the CT milling operation. This paper focuses on an innovative technique for analyzing real-time CT job data that can be used to calculate the required surface weight needed to achieve the optimal weight-on-bit. Furthermore, the technique also enables real -time interpretation of CT job data to confirm that the mill is making the desired progress. This technique has been implemented as a utility within a leading CT modeling software package. This paper will also present field case studies that demonstrate how the new CT interpretation utility software has optimized the milling efficiency in horizontal wells.

Weight-on-bit can be challenging to calculate at surface as downhole motor performance is generally observed from differential pressure and rate of penetration (ROP). If an accurate weight-on-bit (WOB) is maintained, motor performance and ROP can be maximized while controlling debris size. This will increase the efficiency of the entire millout operation. The weight-on-bit can be monitored and manipulated live via new software (Yeung, J. et al. 2015).The objective of this research paper is to conduct a comparative study that analyzes the performance of the five bladed carbide mill, tri-cone and PDC bits in terms of debris size vs weight-on-bit. Two main criteria will be used for the analysis. Firstly, a test will be carried out in order to determine how the set down force affects the drilling tool in terms of generating smaller debris size. This knowledge intends to improve wellbore clean outs and reduce the number of wiper trips. Secondly, the test will analyze how set down force of the drilling tool affects the ROP on the bridge plug. One specific type of 4-1/2Љ bridge plug with a combination of selected mills and bits will be studied in this paper to control the experiment. However, the overall milling parameters may vary greatly depending on the manufacturers, plug, mill, and bit types.A series of bridge plugs will be milled out in a controlled environment using the five bladed carbide mill and tri-cone and PDC bits. Each bridge plug will be milled out using a different weight-on-bit. After the bridge plug is milled out, all the plug debris is collected, and sorted based on a debris size distribution graph. The ROP will also be measured during the milling process to determine milling efficiency.In summary, this paper will compare the performance executed by the five bladed carbide mill, tri-cone, and PDC bits. This paper will identify the optimal weight-on-bit to achieve the desired quantitative debris size with these plugs. More studies need to be conducted for different plug types to see how weight-on-bit affects debris size.

There has been a recent increasing trend in the number of horizontal wells being drilled in recent years. Wellbores are being drilled with various designs that often overlook challenges faced during the completions phase of the wellbore operation. As a result, wellbore intervention has faced some challenges when servicing wells. Although well engineering programs have been developed to optimize the design of the wellbore; one of the limiting factors of wellbore design has become coiled tubing reach capability and set down force at the end of the coil. To address this concern this paper looks to examine the effect of wellbore design on the set down force provided at the end of the coiled tubing string.