A downhole well tractor system was used in Kern County, California, USA, to convey production logging sensors into a horizontal uncemented slotted liner to determine the production profile and later coiled tubing was used to place an annular chemical packer in an effort to shut off water production. The siliceous shale reservoirs of the Monterey formation of Kern County are very different from conventional sandstone and carbonate reservoirs. Production is primarily from thinly laminated porcelanite. One of the fundamental problems that hinder exploitation of the shale reservoirs is accurate identification of hydrocarbon and water resources. Production is achieved through extremely small pores and enhanced through small- to large-scale natural fractures. Drilling and completion techniques include extended-reach horizontal uncemented liner configurations. Several wells have experienced large water cut increases shortly after completion. A flow profile achieved using tractor-assisted production logging sensors showed that approximately 60% of the water was produced from the bottom third of the well. An experimental technique to isolate water production in two uncemented slotted liners was employed with the use of a thixotropic annular chemical packer squeezed via coiled tubing into the slotted liner and slotted liner openhole annulus. The objective of the treatment was to shut off the bottom third of the well to reduce water rates. Several other siliceous shale wells have been profiled, and opportunities for water isolation have been identified. Successful remediations will support the economic viability and longevity of horizontal uncemented liner completions. Historical Attempt to Profile Production For solid cemented and perforated completions isolated interval testing proved the most effective method of locating changing fluid contacts and profiling well production. This technique although relatively cheap and simple lacks the ability to mimic actual production mechanisms. It is well understood that inflow performance needs to be treated as a total system. Interval testing breaks the system into nodes that will not sum up to the system when commingled. This is particularly prevalent in high liquid wells, and wells being produced with gas lift. Other attempts have included the use of a power fluid employed with concentric tubing. The technique consisted of traversing the horizontal well producing section and time and depth matching the flow on surface with the downhole intake. This technique lacked accuracy due to measuring flow rates based on flowing conditions that did not match the actual production scenario and challenges with power and produced fluid segregation on the surface. Slotted uncemented slotted liners preclude the use of isolated interval testing. Concentric power fluids attempts lacked the accuracy and resolution required for proper reservoir management. Therefore the decision to run a comprehensive, integrated production logging tool capable of quantifying flow profile in uncemented slotted liners was chosen. Production Log Candidate Selection Economically based candidate selection revolved around primarily selecting wells that had relatively stable increased water cuts with the potential for water shut off. These increased water cuts invariably resulted in a reduction of oil and gas rates. Secondary objectives of the survey included understanding the production mechanism, i.e. was production well dispersed throughout the horizontal section or was it localized in the toe or heel of the well, what was the contribution from matrix versus fractures, assessing the competence of the formation behind the slotted liners, and determining the effect, if any, resulting from dolomitic tight often fractured streaks in the interval.

Coiled Tubing (CT) equipment in the Norwegian sector of the North Sea has traditionally been heavy, due to CT reels using larger sizes of CT - a trend also observed in other areas. Due to the requirement of performing well interventions in longer wells and larger completion sizes, CT drums weighing 40–60 t have been utilised. Not many platform cranes are capable of lifting such heavy CT drums and during bad weather periods operations are often delayed, even when using significantly lighter CT drums. Using spoolable CT connectors allow for a long and heavy CT string to be lifted on board of a platform on two or more separate drums and joining them together again once onboard. More than 50% weight reduction has been achieved making operational schedules more predictable. In the geographical areas considered, spoolable CT connectors have outperformed traditional methods like boat spooling and butt-welding from a safety, operational and economical point of view. Due to the reduction in weight, larger CT sizes have become available on older platforms as well. New CT applications that were previously considered unfeasible, like selective, high-rate acid fracing through CT, have been performed, extending the capabilities of CT interventions beyond previous logistical and technical limits. Being able to select the correct size of CT, with less dependency on offshore crane limits and weather has a fundamental impact on the usage of CT in the offshore industry. Rather than discussing the spoolable CT connector itself, the primary intention of the paper is to re-view case histories that were performed during the last 5 years. Operational challenges that have been mastered, successes, failures and further developments are presented. A new CT reel configuration to simplify spoolable CT connector installation will be presented. The new applications made possible by this technology and their economic impact on the Norwegian CT market since year 2003 will be reviewed. Introduction Reducing the weight of CT reels has been an ongoing objective, especially in the offshore CT industry. Several methods have been established, ranging mainly from reducing the CT size itself, butt-welding, spooling the CT from a boat to the offshore installation or using split-reel systems (drop in drums). The trend to larger CT sizes observed in many markets during the recent years clearly demonstrates the desire not to compromise on the CT size itself. Especially in markets using larger sizes of CT, split-reel systems have become the standard during day to day operations. Butt-welding and spooling of CT from a boat to the offshore installation has a substantial track record for CT sizes of usually up to 2". All of these methods have their advantages and disadvantages mainly circling around issues like economic feasibility, required special resources for implementation, offshore logistics, operational flexibility and reliability. The development of the spoolable CT connector has been described in previous publications [H.B.Luft et al, 2004]. Field implementation has been successfully performed [L.Link et al, 2005] in the Norwegian and Danish sectors of the North Sea as well as adding new types of CT applications to the conventional CT offshore market [K.Ormak et al, 2003]. The track record established for the spoolable CT connector during the last 5 years in the Norwegian sector of the North Sea clearly indicates acceptance from the operators. It has been recognised as a method of further reducing the lifting weight of CT reels and reliably performing CT operations using larger sizes of CT. Using this method CT strings have been lifted onboard the offshore installations in two or more sections (2 or more CT drums) and joined together using the spoolable CT connector.