Abu Dhabi National Oil Company (ADNOC) and its group of companies completed a review of logging practices in Feb. 2000.1 A recommendation was made to compare PNC tools in a properly characterized well under controlled conditions. This report addresses that recommendation by comparing the accuracy, repeatability and reproducibility of two new and two older generation PNC tools currently available for field monitoring in Abu Dhabi reservoirs. Tools are compared against each other and to core measurements. Elemental analysis of core and reservoir condition fluids provided the benchmark for formation capture cross-section comparisons. One tool displayed much poorer statistics than the other tools. All tools suffered from large inaccuracies in their auxiliary porosity measurements. Reproducibility was good for sigma measurements but poor for porosity. Three of the four tools are acceptable for qualitative field monitoring operations. Two of the tools are preferred for accurate residual oil measurement.
Expandable tubular solutions have been developed and applied as a drilling solution to extend well depth while maintaining a larger borehole diameter . In this paper we review the benefits of expandable tubulars for shut-off and zonal isolation in carbonate reservoirs. Particular emphasis is given on a major Middle East Operator's experience.
Expandable open hole liner (OHL) systems, developed as a drilling solution, is based on expanding a liner across an open hole section and into the previous casing to form a liner hanger . Instead of cement, elastomer seals provide zonal isolation in open hole , .The liner is expanded to create a seal by energizing an elastomer between casing and the formation. In addition the elastomer swells in contact with water. This dual sealing mechanism provides an annular seal of any desired length. The technology is non-invasive on the reservoir. Alternative technologies either are invasive on the reservoir or have had limited success, i.e. cement, chemical squeezes or scab liners.
Expandable tubular solutions have proven successful in terms of installation reliability, isolation of fractures, swept zones and ghost holes. Also, the technology enabled inflow profile control through zonal isolation in horizontal wells. Case histories for shut-off and zonal isolation demonstrate the viability of extending the scope of expandable technology deployment for better management of carbonate reservoirs through a "drill, monitor & intervene" completion philosophy combining selectivity and shut-off in a low-cost intelligent completion solution.
A shift from content-based to activity-based learning is taking place at the Shell Open University (SOU), with already more than 100 course events redesigned from a classroom only model to this new model. It emphasizes work-based activities, supervisor involvement, and sharing of knowledge and experiences via a blend of formal and informal learning. Results to date and lessons learned are presented.
This study is about finding the best suitable secondary / tertiary oil recovery methods for the Zaqeh field which is one of the heavy oil reservoirs located in S.W of I.R.Iran.
This reservoir is selected because of it's high pressure(14690 psig), high temperature(246 F), and having very deep(13895ftss) / thick pay zone(820 ft) with respect to other neighboring heavy oil reservoir(Table 1).
After reviewing the applicability of processes, the technical feasibility of each method is carried out by screening procedure based on process characteristics, reservoir and fluid properties and finally pre-designs the selected method.
Based on the reservoir specification, it seems that oil recovery by primary depletion mechanism would be low (approximately 7-10%) and reservoir pressure would decline rapidly. To avoid high lifting cost and increase the reservoir oil recovery factor decision was made to use a pressure maintenance project that relies on EOR process.
After screening, it is found that the In-Situ Combustion is the applicable process for this reservoir. This selection was further approved when it compares with approximately similar reservoir (West Heidelberg in Jasper Country, journal of petroleum Tech., 1983).
By this method the ultimate oil recovery of the Zaqeh field would be reached to about 60%.
ZADCO owns more than 500 wells operating in UZ, UA & ST fields to contribute in achieving the production targets as set by the Shareholders. To ensure that wells operate as designed for their assigned life (or greater) with all risks kept as low as reasonably practicable or as mentioned, it is important to insure individual well's integrity. Hence, ZADCO developed an in-house "Well Integrity Management System (WIMS)", which defines & provides the operating standards & guidelines for maintaining the well integrity parameters, ensuring safe well operations and securing well potential availability during its life cycle so that return on investment is maximized without the sacrifice of safety and environment.
The implementation of ZADCO's well integrity process follows the cycle assurance testing, preventive measures, monitoring, evaluation / assessment, control & remedy, audit / verification.
This paper reviews WIMS in ZADCO. WIMS is structured to include wellhead (surface) equipment, downhole equipment and operational (process control). WIMS places much emphasis on the requirement of barriers for safety and environmental protection.
Almost every drilling operation is a potential source of damage to well productivity, lost circulation, differential sticking and other related conventional Drilling problems.
This paper re-visits the key damage mechanisims and provides a broad overview on how they occur during various oilfield operations, and their effect on well productivity. Also, lost circulation or fluid invasion potential in high permeability zones, large open fractures, heterogeneous carbonates with massive interconnected vugular porosity, or pressure depleted zones would be a major issue of concern during conventional drilling condition. The worst-case scenario would be a combination of one of these high permeability features with significant pressure depletion.
In order to overcome the above problems while drilling, the industry developed a method to drill with a bottom hole pressure below the pore pressure, called Underbalanced Drilling - UBD
As the majority of hydrocarbons being exploited today are found in existing pressure depleted or complex and lower quality Reservoirs with lots of the conventional drilling problems, this is where Underbalanced Drilling Technology can add value and in some cases reduce development cost. Soon, Underbalanced Drilling will become the standard field development technique, both Onshore and offshore, where the Geology and Reservoir are suitable.
The paper reviews several case histories and real results highlighting the advantages of Underbalanced Drilling Technology in reducing Formation Damage, Lost Circulations and improving well productivity.
The field is a very mature field. 30 years after its production start-up, it is now producing with an average water-cut of 84 %. This paper presents the continuous adaptation efforts deployed throughout the years to further valorise resources, in response to the growing maturity of the field.
Well activation started very early, first through ESP's, then by full field gas-lift implementation. As an answer to an important depletion of some reservoirs, a water injection scheme has been implemented as early as 1979. In 1997, a major field revamping campaign was performed to implement an EOR technique which proved to be very efficient: tertiary gas injection after water flooding. After the first horizontal wells, drilled in 1994, ever increasing well architecture complexity allows now to target more and more precisely heterogeneities, to produce residual oil pockets, and to develop tight reservoirs. A 3D seismic acquired in 1995 has opened the path for quadruple and quintuple multilateral wells.
At the current maturity level, field management appears as the next challenge. The complex gas scheme, which comprises at the same time gas production, gas lift, gas injection, gas recompression and gas export, needs constant arbitration between activation gain and tertiary recovery.
In parallel, a global water management policy must be set up, as the water disposal network is more and more heavily loaded. A water management study is currently under the way, to review long term fluid production predictions, surface facilities limitations, and long term reliability of disposal well, and to screen for solutions, ranging from reservoir and well control to surface facilities de-bottlenecking.
The motion of oil ganglia and droplets in chamber-and-throat pore networks in two-phase flow in porous media can be modeled without or with wetting films. The existence of wetting films around ganglia and droplets is favored by small contact angles (say, smaller than ca. 10 deg) and wall roughness.
The predictive model DeProF (Decomposition into Prototype Flows) considers steady-state two-phase flow in porous media as a composition of three flow patterns, namely connected-oil pathway flow, ganglion dynamics and drop traffic flow. The key difference between these prototype flow patterns is the degree of disconnection of the non-wetting phase (‘oil') which, in turn, affects the relative magnitude of the rate of energy dissipation caused by capillary effects compared to that caused by viscous stresses. The observed flow is usually a mixture of the basic prototype flows.
In the present work DeProF is used to investigate the effect of the wetting film on two-phase flow in typical 3-D pore networks by including wetting films around droplets. The effects of the wetting film are assessed by comparing the values of key physical characteristics of two-phase flow, specifically, the interfacial area per unit volume, the mechanical power dissipation p.u.v., the degree of disconnectedness of the non-wetting phase, and the energy utilization factor, which are obtained with and without wetting films.
The ADNOC (E&P) group's Emiratisation targets have highlighted the need for competency development of UAE nationals. One issue within development is the nature and delivery of training. This in turn raises the important issue of the language of instruction, technology and business and the concept of English language competency. Another issue is that underlying any instructional methodology are sets of beliefs and values. Any mismatch between these and those of trainees has implications for the value/uptake of that training. Insights from a unique empirical study with a group of UAE nationals provide information about their preferred learning styles and cultural values. The findings have implications for understanding and optimising the learning and development process within the workplace, and illustrate the value of research within such a context. Setting competence descriptors and objectives are not the only considerations when developing a competent workforce.
Residual Oil Saturation (Sorw) is a critical reservoir model parameter for evaluating reserves in the Greater Burgan Field. Past Sorw studies in Greater Burgan Field either looked only at core test data, or only looked at cased-hole log data. None of the past studies considered areal position, different rocktypes, or changes in remaining oil saturation with varying amounts of water sweep.
This study includes analysis of Sorw from open-hole water saturation, Time-Lapse PNC data and Special Core Analysis water flood experiments.
The majority of the log data in Greater Burgan Field water - swept zones are concentrated in the 3rd sand middle, 3rd sand lower and 4th sand formations. The comparisons of the results from all three methods used in the study to measure remaining oil saturation (ROS) are limited to these reservoirs.
Results from these methods were remarkably consistent.
All reservoir sand with extensive PNC log data showed that zones encroached by water for 22+ years tend to be at or near residual oil conditions. Measurements in the zones with water encroachment for less than 22 years have about a 50% chance of being incompletely swept. Analysis of the 22+ year data allowed reasonable ranges of Sow were estimated from this data.
Investigations of ROS spatial variations in the Magwa, Ahmadi and Burgan sub-fields were made. 3rd sand middle was the only reservoir with both adequate PNC and open-hole coverage in ROS from these three areas in Greater Burgan Field.
ROS by rocktype was reviewed in three categories of reservoir rock (excellent, medium and poor quality reservoir) as currently defined by log analysis in Greater Burgan Field. The vast majority of log data occurs in rocktype 1, the highest quality reservoir rock. Only 3rd sand lower formation contained sufficient data in all three reservoir quality rocktype to make valid comparison. Both core flood Tests and PNC Time-Lapse methods also showed no difference in ROS based rocktype.