Zapolyarny District
Abstract It is important for wells in the Yuzhno-Khylchuyu field (Russian Arctic region) to have sufficient zonal isolation and thermal protection between production casings and the permafrost media because they will initially be produced with high flow-rates. High cement integrity helps prevent the permafrost from thawing therefore alleviating problems associated with the creation of unwanted cross-flows and eventual casing deterioration. Low-density cement slurry has been used as an alternative to foam cementing because it contains hollow microspheres which help decrease cement thermal conductivity. The use of hollow microspheres in cement blends creates further challenges for engineers with regards to slurry optimization. Special attention is given to slurry properties because the presence of hollow microspheres can influence slurry rheology, increase cement setting time, and act negatively on compressive strength development. The optimization of slurry design takes all of these parameters into consideration while resolving the problem of heat insulation, thus helping reduce the chance of primary cementing failure over the life cycle of the well. The optimization of the cement slurry design makes it possible to significantly decrease the initial cement setting time, provide high compressive strength, and resolve the problem of heat insulation. Introduction Preservation of the cement-sheath and heat-insulation properties is one of the most significant challenges during development of cement slurry design for permafrost intervals ("Cement Blends can be tested for Arctic Environments"). There are several ways to resolve this issue. Using hollow microspheres is the most cost-efficient method. However, there are a number of issues with hollow microspheres that can negatively influence cement slurry: reduced cement-sheath strength, increased cement setting time, and deterioration of rheological parameters. These issues can cause mixing slurry to be more difficult. This paper provides a summary of the methods used to prepare optimized cement slurry with hollow microspheres for use in permafrost intervals. Discussion Oil production at high flow-rates has been connected to permafrost thaw problems, resulting in a need for development of an optimized cement slurry to provide good heat-insulation between a casing and formation since the temperature of extracted hydrocarbon fluid is 57°C. Permafrost at theYuzhno Khylchuyuskoye field is represented by the Quaternary system. The depth is 185 m. The icy layers are at 0 to 10 m below icy rocks. The standard well construction at the Uzhno Khylchuyuskoye field is: 640-mm conductor in 910-mm openhole to 30 m, 340-mm surface casing in (406.4 mm) openhole to 650 m, and 244.5-mm production casing in 311.1-mm hole to 3000 m. The 630-mm conductor casing covers the icy layers from 0 to 30 m (Fig. 1). At the development stage of the Yuzhno Khylchuyuskoye field, the design institute prepared a thermal engineering analysis based on thermal conductivity coefficients of the materials used in well cementing (Fig. 2). According to this analysis, the problem with permafrost thawing was resolved by using a slurry that contains hollow microspheres at a concentration of 20% BWOC. The company used a cement slurry containing gypsum for cementing in permafrost for long periods of time. Initially, the original cement slurry, with a density of 1.47g/sm, containing 20% BWOC of hollow microspheres and 160% BWOC of gypsum-based additives was used for cementing the 640-mm conductors. In this case, G cement was used.
Abstract LUKoil and ConocoPhillips formed the joint venture company NaryanMarNefteGaz (NMNG) to develop jointly owned licenses in the Timan-Pechora Basin. The Yuzhno Khilchuyu license lies in this province and, is expected to be one of the largest and most prolific fields in the region. Development of the Yuzhno Khilchuyu Field requires a huge initial investment in infrastructure, drilling and transportation. Successfully achieving acceptable reserves and production levels from the field will be critical to offset these investments. To meet this challenge a more detailed understanding of the reservoir is needed to optimize well placement. In 2004, a large multi-disciplinary subsurface project team was formed with members from LUKoil, ConocoPhillips and Fugro-Jason to develop updated high-resolution geologic and reservoir simulation models. The seismic and well log data were completely reprocessed, resulting in a significant improvement in the overall data quality. All log, core, and production test data were incorporated into a new, fully integrated, interpretation. A sophisticated Markov Chain Monte Carlo (MCMC) geostatistical inversion methodology was applied, and the resulting high-resolution geologic model yields a dramatic increase in reservoir detail. The new model enabled the team to define the aerial extent of different reservoirs and the distribution of internal barriers. It also provided insight into porosity and permeability distribution within each reservoir, enabling better decisions on the location of production and water injection wells. Development drilling is in progress. Introduction The NMNG joint venture agreement between LUKoil (70%) and ConocoPhillips (30%) was consummated in 2005 and is comprised of two exploration and eleven production licenses. The NMNG assets are located in the Nenets Autonomous Okrug, situated in the northern Timan-Pechora Basin onshore region (Figure 1). The hydrocarbon bearing sequences are predominantly carbonates and secondarily siliciclastics ranging from the Silurian to the Triassic. The Yuzhno Khilchuyu Field is considered to be the most prolific of the NMNG joint venture portfolio. The Yuzhno Khilchuyu Field reservoir characterization re-interpretation project that commenced in late 2004 and ended in early 2006, was carried out by an integrated technical team from Fugro-Jason, NMNG, ConocoPhillips, and LUKoil (Guilloux, et. al., 2006). Although Fugro-Jason had the accountability of executing and completing the project, ConocoPhillips, LUKoil and NMNG collaborated with Fugro-Jason on a regular basis to facilitate knowledge sharing, validate and understand interim results and to ensure the resulting high-resolution geological model would initialize in the selected reservoir simulation software. Collaboration activities included participation in interim work sessions and implementation of milestone-related peer reviews and project reviews with pertinent company specialists and management. Additionally, ConocoPhillips prepared a secondary ‘shadow model’ utilizing Petrel to aid in validation of the project as it progressed. The three companies contributed to the project management and all major technical project tasks including data discovery and collection, seismic reprocessing, seismic inversion, petrophysics, rock physics, interpretation (seismic, geology, biostratigraphy), petrophysical cluster analysis, stochastic porosity simulations, high-resolution geologic modeling and analysis. The ongoing and successful collaboration between the three companies and Fugro-Jason contributed significantly to the success of the project and ensured alignment of interim and final results with each company and defendable project results. Although a technical interpretation of the entire hydrocarbon-bearing sequence of the Yuzhno Khilchuyu Field was carried out during the project, this paper will focus on the reservoir characterization of the principal oil-bearing deposits in the Lower Permian Asselian-Sakmarian carbonate sequence.
- Geology > Geological Subdiscipline > Stratigraphy (1.00)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (0.88)
- Geophysics > Seismic Surveying > Seismic Processing (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling > Seismic Inversion (0.66)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.46)
- Europe > Russia > Northwestern Federal District > Northwestern Federal District > Nenets Autonomous Okrug > Timan-Pechora Basin (0.99)
- Europe > Russia > Northwestern Federal District > Nenets Autonomous Okrug > Zapolyarny District > Timan-Pechora Basin > Pechora-Kolva Basin > South Khylchuikoye Field (0.99)
- Europe > Russia > Northwestern Federal District > Komi Republic > Nenets Autonomous Okrug > Timan-Pechora Basin (0.99)
- (24 more...)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Geologic modeling (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)