TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractFor many years, various types of simple nozzles have been regularly used for wellbore cleaning with coiled tubing. This paper describes the advances made in fluid jetting technology, associated tools and the parameters that are crucial to the efficiency of these techniques. A laboratory and field testing programme has been completed and data is included. By detailed design of the internal fluid path, orifice geometry, jet stand off and pump rates, tool effectiveness has now been improved to a level several times more efficient than previously available for the same feed pressures and flow rates. Pre-engineering using computer simulation to optimise the job design parameters has proven essential in designing clean out jobs and sizing the appropriate coiled tubing and pumping equipment. Three distinct categories of tools have emerged; conventional drilled nozzles, non-rotating high-pressure nozzles and high pressure rotating tools. All three types have gained a common advantage from the development of a Downhole Phase Separator. The high-energy losses previously associated with a two-phase fluid necessary in low hydrostatic wells can now be eliminated. A step change in operational efficiency has resulted through combining the major improvements in jetting tool design with the ability to separate gas and liquid phases downhole. With this development, the full benefits of using single phase fluid jetting can be realised in low hydrostatic wells.

Horizontal completions continue to increase in popularity throughout the industry. In North America the majority of horizontal wells are drilled in shale gas formations. These formations require fracture stimulation for economic production. The majority of these stimulations are completed by fracturing four to six clusters of perforations simultaneously at high rates followed by a mechanical isolation with a composite bridge plug. As the horizontal wells increase in length the number of plugs required increases, with up to twenty plugs not being uncommon. These plugs are removed with a positive displacement motor (PDM) and mill run on either coiled tubing (CT) or jointed pipe. In longer-reach horizontal completions, plug removal using CT becomes more challenging as the efficiency of surface end loads transmitted to the mill are reduced. Quite often the deepest plugs can not be reached with standard coiled tubing, instead requiring larger-diameter, more costly, coiled tubing or jointed pipe. The need to extend the operating depth to effectively operate PDMs and reach the deepest plugs has led to development of several tool systems. This paper will discuss the engineering, design, testing and initial field trial results of a variable fluid hammer extended-reach tool; how it was used to improve plug milling performance, to give superior control of weight on bit, to extend coiled tubing reach in the horizontal section and to reduce operational time. These field results will be compared with results using other methods of friction reduction, such as pipe-on-pipe friction reducers.

Cemented Single Point Entry (CSPE) has the potential to reduce or eliminate the non-uniformity and Hydraulic Frac Stimulation (HFS) placement uncertainties inherent in other completion systems. If entry-to-entry isolation can be achieved, HFS initiation and treatment allocation near the wellbore can be better controlled by a CSPE completion. Fiber Optics (FO) and other diagnostics can provide the means to evaluate the effectiveness and potential benefits of this and other completion systems. This paper describes the HFS placement findings of a FO instrumented Coil Tubing activated CSPE well (CTa-CSPE). Coil Tubing CSPE completions provide some additional frac diagnostic information. Pressure and Temperature (P/T) gauges located in the Coil Tubing Bottom Hole Assembly (CT-BHA) help to evaluate the isolation with prior stimulated stages. A newly developed sleeve, specially designed to accommodate a FO cable outside casing, allows the simultaneous acquisition of both P/T information from downhole gauges and high-resolution stimulation data from FO. This paper shows several examples from stages with variable entry-to-entry isolation quality in a wellbore with 6000 ft lateral section. The results from the P/T gauges, Distributed Acoustic Sensing (DAS) and Distributed Temperature Sensing (DTS) are mostly consistent for all 69 stages in this well. Only stages where communication was observed toward the heel-side of the lateral, relative to treatment sleeve, show inconsistent but explainable results. CT-BHA P/T gauges are only capable of detecting communication toward the toe-side of the lateral. In this well some degree of communication occurred in 48% of all stages. Evaluation of the FO data across multiple stages shows that the path of communication between sleeves and slurry placement can be complicated. Integration of DAS and DTS indicates that the slurry, between adjacent and poorly isolated stages, travels behind the casing down to the prior sleeve and then inside the wellbore, where the slurry is partially re-injected into previously stimulated stages. This dataset clearly illustrates that no single HFS diagnostic provides all the necessary information to fully understand the complexities of HFS placement. In this well, the data from CT-BHA P/T gauges, DAS and DTS are clearly complementary. The data also indicate that there is an urgent need to improve isolation between stages. Cement quality seems to be the primary source of entry-to-entry communication in long horizontal wells for this and other completion systems. In this well alone we estimate several hundred thousand US$ were wasted from the misplacement of stimulation energy and materials (capital inefficiency). To capture the full value from CSPE "pinpoint-fracturing" and the corresponding more effective drainage of resource volumes between wells, the problems associated with entry-to-entry communication must be understood and corrected. Finally, we will introduce some new multicycle sleeves that will further enhance the capabilities of CSPE systems. These sleeves are specially designed to obtain production profiling information via FO. Deployment of such systems should provide the industry with the means to better evaluate and optimize completions and wellbore spacing.

TX 75083-3836 U.S.A., fax 01-972-952-9435. AbstractA large number of fields worldwide have sand production problems and a common solution is a gravel pack (GP) completion. Over time this GP can become plugged with production fines as well as solids that may precipitate out of the produced fluids. As the GP plugs, it creates a larger restriction to flow and the production rate will decline. At some point the operator will decide the production rates are no longer acceptable and intervention is required. As a result, the GP completion will either be pulled from the well or be cleaned in-situ.Previous in-situ cleaning processes involved treatment fluids bull headed into the well or placed by coiled tubing, to dissolve GP plugging damage. This paper describes a new method for cleaning a GP insitu. The process involves a rotating jetting head to create specific pressure pulsations combined with angled nozzles to create a "circulation current" within the GP. These circulation currents are localised and result in a temporary increase in GP permeability ensuring that treatment fluid will invade the GP only in the area immediately adjacent to the tool. This new process is significantly more efficient at unplugging the GP than previous methods and treatment fluids can more effectively reach areas of the completion such as the perforation tunnels and drill-in fluid filter cake damage. This process also includes managing the jet impact pressure to ensure that fragmentation damage of the GP proppant does not occur.The paper will report results of laboratory tests using existing wash methods compared with the new technique and demonstrate the differences in; treatment fluid placement efficiency, fines removal efficiency and damage caused to the GP proppant.