Production from heavy oil reservoirs has always been a challenge due mainly to one factor in particular high oil viscosity, implying low oil mobility within porous media. Different methods have been implemented over the years in order to reduce oil viscosity. Well-known methods include steam injection (e.g., Steam Drive, Steam Assisted Gravity-SAGD), CO2 injection, chemical injection etc. These types of application are mainly applied to onshore fields where space is available and operating costs are much lower with respect to offshore fields. Moreover they may not be feasible for shallow reservoirs where injection could be an issue due to uncertainties regarding the cap-rock sealing. The scope of this paper is to present a patented nonconventional EOR method for heavy oil reservoirs using radio frequency/microwave heating. An adequate completion design and well-reservoir connection is used for heating the oil, thus solving the problems that impede RadioFrequency /MicroWave (RF/MW) penetration into the reservoir. Consequently, oil viscosity may be reduced, thus allowing its continuous production to surface (eventually by means of an artificial lift system included in the well completion). This method could be also suitable for offshore fields because it doesn't require high energy consumption, or large surface areas, or high operating costs. It can also be suitable for those shallow reservoirs not suitable for injection processes. This paper presents details of this new technology and associated simulation results showing its range of implementation.

Many West Africa Offshore Fields are maturing and operators are completing secondary targets in their wells to maintain the economic operation of their valuable assets. However, off-shore environment makes the capital expenditure associated to this kind of interventions of critical importance. It follows that the selection of the right and most remunerative activities is crucial. In the Kitina Field, offshore Congo, deeper sands have been produced to economic depletion and reservoir studies allowed the determination of alternative production intervals for production maintenance. Large quantities of reserves can be found in low permeability, consolidated, formations as well as in very deep and remote culminations. During the first semester of 2007, the Kitina field production increased of 160% reaching a production level lost since early 2004. This was achieved with a variegate set of actions on different reservoirs:infilling the Kitina South culmination with the long reach and ultra deep well KTM-SM5,a massive multistage hydraulic fracturing campaign carried out on the three wells draining the low permeability 3A reservoir and 3rd) with the sweep optimization of the reservoir 1A. Eight propped hydraulic fractures were placed in three re-completed, cased-hole wells with very significant production improvements. These represented the first applications in Congo of different technologies opening a wide range of further applications in similar environments. The paper describes the 2007 and 2008 Kitina rejuvenation campaign with an eye to all the disciplines involved, from reservoir engineering and modeling, to operation geology, drilling and completion, production. The papers focuses with more detail on the successful multi-stage hydraulic fracture campaign from the preliminary design and production forecast pre-job to the reservoir model history match and forecast phase post-job. Interesting reservoir engineering overviews of the future development of the field via improved and enhanced oil recovery techniques are also presented. Introduction Existing oil and gas fields are maturing and new finds are more complex to discover and produce. In today's oilfields portfolio, mature reservoirs production maintenance and increase represent the biggest challenge to face over the next decades to meet the continuously increasing demand for hydrocarbons. Technology research, development and innovation have been the recent answer to sustain the world's oil and gas production and will continue to be so. However, new developments in technology need professionals who are taking the risk of testing them keeping in mind that the failure can be sometimes only a temporary and/or necessary stop towards the success. Mature fields can represent the "working ground" and "technological gyms" where to test new techniques with the final aim of accelerating and increasing reserves. Mature fields have to be seen today as opportunities for improvement rather than declining assets. Accurate candidate selection, optimized treatment design, sound reservoir modeling of production forecast represent crucial and interdependent factors for successful economic evaluations.

No abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe management of producing wells activated with ESP pumps has to take into account several problems: limited pump run life, production losses due to multi ESP failure and shut in wells.• pump run life increase not quantified due the test's short durationThe advanced information provided to the decision makers brought additional benefits to oil company leading to early production recovery, improvement of well inflow and outflow performance knowledge.The Smart Alarms approach can be also applied to other well typologies and data sources.

Hydraulic fracturing operations in West Africa are not as common as in the US, Latin America and the Middle East. In the Republic of Congo fracturing technology is spreading and has overcome more than few difficulties since the practice began. The most significant challenge has been the formation, which has shown through laboratory testing to be soft and watersensitive. The fracturing project started in the laboratories, identifying critical issues, such as formation heterogeneity, hardness, water sensitivity, clay content and particularly the risk of proppant embedment. The fracturing fluid chosen for the project was a water-based, borate-crosslinked guar fluid, with specific chemicals added to minimize formation softening and clay swelling issues. A specific pumping strategy was implemented when using waterbased fracturing fluid to limit the effects of proppant embedment. Several wells were treated with this system. In an effort to improve well productivity, a pilot test was designed with oil-based fracturing fluid. This fluid was pumped in two wells, resulting in improvements in terms of cleanup time and economics, compared to the water-based treatment fluids in the same field. Part of the economic benefit was gained because of the reduced hydrostatic head of the oil-based fracturing fluid, which eliminated the need for a coiled tubing gas lifting operation. Economics were also improved by minimizing rentals of well cleanup equipment because the broken fracturing fluid can be sent directly to production facilities. In this paper, design and application results for the oil-based fracturing fluid operations are presented with all the operational and logistical challenges overcome.