TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractWellbore debris is responsible for many of the problems and much of the extra costs associated with producing wells, especially in extreme water depths and highly deviated holes. Even a small piece of debris at the right place at the wrong time can jeopardize well production. For this reason, debris management has become a chief concern for oil and gas producers. Considering rig rates and completion equipment costs, debris removal is moving into the realm of risk management.A clean wellbore is not only a prerequisite for trouble-free well testing and completion; it also helps ensure optimum production for the life of the well. Debris left in the wellbore can ruin a complex, multi-million dollar completion; it can prevent a completion from reaching total depth. And chances are, it will never reach an optimum production level.These issues are pushing the industry to create reliable, efficient systems for quickly ridding wellbores of harmful debris and larger pieces of junk. This paper describes a vectored annular cleaning system (VACS) that can be used alone or in conjunction with any of an assortment of improved casing scrapers, brush tools, downhole magnet subs, downhole filter tools and junk catchers to optimize the efficiencies and economics of debris removal and save trips. This paper will focus on the use of the vectored annular cleaning system to collect and remove debris from areas of the wellbore that traditionally are problematic; i.e., above liner tops, where casing size changes, areas with a loss of annular velocity, and wells with little to no circulation. Case histories from the Gulf of Mexico, North Sea and other areas of the world will demonstrate how this technology has reduced problems of debris removal while saving rig time by eliminating trips.

TX 75083-3836, U.S.A., fax 01-972-952-9435.Abstract A simple spreadsheet model has been developed to estimate Original Gas In Place (OGIP), layer productivity and recoverable reserves for wells with commingled production, completed in multi-layered tight gas reservoirs. Differentiating the productivity between multiple layers of contrasting permeability is old technology. This model, however, replicates the observed material balance trend while also honouring total well production data by varying layer properties. The P/Z trend of the higher permeability layers and lower permeability layers is mapped to "envelope" the productivity index (PI) weighted P/Z curve that is used to match historical data. This technique has been made applicable to the multi-layered reservoir environment by grouping the various kh terms, from all "high permeability" layers, into one model layer and all "low permeability" kh values into the "tighter" model layer. Published literature 1 has already shown that the generation of the layer P/Z curves is applicable for reservoirs with permeability in the range of 0.1 to 10 md. The model has been successfully applied to match and predict the productivity for various wells in Cooper Basin fields, with permeability in this range, and P/Z plots that exhibit curvature. Case studies show that any change in bottom hole pressure conditions (eg. compression) or skin (eg. stimulation) can also be accounted for in the model. Various simulation models have been generated to confirm this technique's applicability to wells in Australia's Cooper Basin, and to establish the PI weighting method.

Debris management is a major concern for producers. Wellbore debris is responsible for many of the problems and much of the extra cost associated with extreme water depths and highly deviated holes. This paper discusses procedures and tool systems developed to optimize the efficiencies and economics of debris removal. Issues pertinent to deepwater wellbore cleaning will be discussed, along with the problems associated with removal of debris caused by perforating, milling, etc. The authors will outline techniques for removal of this debris and discuss a tool system that is a workable solution for these problems. This paper will focus on the use of a Vectored Annulus Cleaning System to remove debris from areas of the wellbore that have normally proven very difficult. The system has been shown to be effective in removing debris from problem areas such as above liner tops or where casing size changes, areas with a loss of annular velocity, and in wells with little to no circulation. Case histories from the Gulf of Mexico and the North Sea will demonstrate how this technology has reduced problems of debris removal while saving rig time by eliminating trips.

There are many situations that require the removal of a production packer from a wellbore, whether it is a planned workover or a stuck packer during the completion process. In all cases, the packer must be washed over and recovered or milled up and pushed down to the bottom of the wellbore. Most of the methods used today are the same tools and techniques that have been in use for the last 30 or so years. These methods incorporate a shoe or milling head with a specific type retrieving tool to catch the packer after milling away the slips, and were designed for packers that came with millout extensions or blank bottoms. Today, however, packers are being run with seal bore extensions instead of millout extensions. Packers are being manufactured with more exotic materials and high chrome metals. These materials present a milling challenge -- not only do they create longer milling times, but they also usually require two or more trips to mill and recover the packer. A new method of milling has been specifically designed to reduce milling and trip times in these modern packers. This new method allows an operator to engage a smooth packer bore and completely remove all of the packer material and slips rather than removing only the outside material and leaving the packer mandrel. This milling procedure is quicker and produces smaller amounts of debris, therefore reducing milling times. The milling heads can be dressed with the most up-to-date cutting structures that will optimize the removal of the packer material depending on whether it is standard grade or of a high-tensile, high-chrome content. This paper will discuss the process and operational procedures pertaining to this new method, along with case histories. The paper will detail the advantages of this method and the tools used, as opposed to the conventional methods and tools that are widely used through out the world today. Introduction Many companies manufacture permanent production packers and accessories. When these packers must be removed, whether it is planned or unplanned, efficient removal will greatly benefit the producing company. This is especially important in the deepwater environment where rig rates are high. The two main processes in accomplishing this task are milling and recovery. Longer milling times or multiple trips in hole to recover debris will produce a lot of non productive time. First let us briefly discuss packers and accessories in general. The packer consists of a packer mandrel with a packing element around the outside. A set of bottom slips prevents the packer from moving downhole and a set of top slips prevent it from moving uphole. In most applications there will be accessories such as seal bore extensions that are run below the packer to allow for longer and more sealing elements to seal off inside the mandrel and seal bore extension. Between the packer element and slips there will be some type of metal rings. Also the length from the top slips to the top of the packer will vary depending on the manufacturer. These packers can also be manufactured for hostile environments and may be made out of the more exotic metals that make milling very difficult with conventional methods. These packers produce longer than normal milling times and require more trips.

Debris management is a major concern for producers. Wellbore debris is responsible for many of the problems and much of the extra cost associated with extreme water depths and highly deviated holes. This paper discusses procedures and tool systems developed to optimize the efficiencies and economics of debris removal. Issues pertinent to deepwater wellbore cleaning will be discussed, along with the problems associated with removal of debris caused by perforating, milling, etc. The authors will outline techniques for removal of this debris and discuss a tool system that is a workable solution for these problems. This paper will focus on the use of a Vectored Annulus Cleaning System to remove debris from areas of the wellbore that have normally proven very difficult. The system has been shown to be effective in removing debris from problem areas such as above liner tops or where casing size changes, areas with a loss of annular velocity, and in wells with little to no circulation. Case histories from the Gulf of Mexico and the North Sea will demonstrate how this technology has reduced problems of debris removal while saving rig time by eliminating trips.