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Using An Integrated Approach to 
Production
Optimization in A
Mature Field: Burgan Field*
By
Satyendra P Sinha1, Ibrahim Al-Kandar1, and Khalaf Al-Anezi1
Search and Discovery Article 40183 (2006)
Posted January 12, 2006
*Modified from extended abstract prepared for presentation at AAPG International Conference, Paris, France, September 11-14, 2005
1Kuwait Oil Company, Ahmadi, Kuwait
Abstract
Production
optimization ensures that wells and facilities are operating at their peak
performance at all times to maximize production. Frequent changes in well and
surface equipment down time, maintenance work, evolving reservoir conditions
etc. usually make it impossible for the team to keep the asset tuned for optimal
operating conditions. The current manual production optimization approaches are
both time consuming and error prone due to the complexity and large volume of
data that have to be considered. In the present work, several tasks and
processes have been streamlined and automated with effective linkages to achieve
a near real time optimization. The measure–calculate-control cycle is
implemented every twenty-four hours, a procedure which maintains the system at
optimal operating conditions almost all the time. Used on a daily basis to
manage mature assets and make operational decisions, the system integrates
production data management and reservoir modeling with transient pressure
analysis, well modeling, and surface network modeling optimization. A sequential
non-linear programming solver is used to optimize hundreds of critical
parameters.
A
multi-disciplinary team approach has been used to implement the process of
production optimization using Internet, computer network, communication links,
timely team meetings and corporate database. The focus has been on reducing the
cycle time for conversion of data to information, decisions, and actions by
developing an appropriate system. The benefits of optimization are significant.
Gains include a moderate improvement in uptime, along with a significant
improvement in produced volume and overall reduction of lifting and operating
costs.
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IntroductionGreater
Burgan Field of Kuwait has nearly six decades of The
number of completions in each reservoir is shown in
Figure 2a. There are four reservoir units in
the Burgan Formation: Third Sand Upper (3SU), Third Sand Middle (3SM),
Third Sand Lower (3SL), and Fourth Sand (4S). The Wara and Burgan
reservoir units have the same original oil-water contact. The 3SM and 4S
reservoirs are mostly massive sandstone reservoirs, whereas the Wara,
3SU, and 3SL are interbedded sandstone and shale. However, the third
sand middle contributes the major bulk of
The present work describes the process of managing facilities, wells,
surveillance, and well work with a series of automated tasks, data
validation, data analysis, reservoir models, and optimization solver to
achieve
Facility LimitsThe main components of facilities at GC-I are:
An outline of GC-I components is shown in Figure 4, and the schematic is presented in Figure 5. The facility limits in GC-I prove to be a bottleneck in the GC deliverability. In case adequate attention is not paid to balancing the fluid streams, it may become difficult to reach the peak performance of the GC as a whole. In GC-I the HP dry and LP dry separators can both handle 77,900 bfpd with salt up to 10 gm per thousand barrels. At present, GC-I processes dry crude of nearly 55 Mbopd. On the wet side, HP wet & LP wet separators can both handle 77,900 bfpd. Wet tank oil capacity is 91 Mbopd, and water handling capacity is limited to 27 Mbwpd. Desalter can handle 60 Mbopd. However, GC-I is currently handling 65 Mbopd and 18 Mbwpd in wet stream. A maximum of 20,700 bwpd can be disposed, 15,700 bwpd into evaporation pits and 5000 bwpd into effluent water injector wells. Transit pump capacity is 120 Mbopd, and CRU can handle 8.8 MMscfd. CRU capacity can vary from 120 Mbopd to 135 Mbopd of equivalent oil depending upon the amount of tank vapor. Six completions (3 pair of completions) have commingled flow-lines. However, in two pairs, only one completion is open, and the remaining pair has both dry completions open. Endeavor is being made to segregate this pair of ZA-18 casing & ZA-83 tubing completions perforated in Wara and Third Sand Middle reservoirs, respectively. This is expected to add 700 bopd to GC-I.
Wara Reservoir StrategyAs seen in the stratigraphic column, Wara sandstone reservoir lies at the top of the sequence. Most of the area, being distant away from the aquifer, does not have any significant energy support. More than 15% of STOOIP has been produced from the reservoir causing the reservoir pressure to decline below the saturation pressure. This has resulted in high gas saturation largely in the updip part of the reservoir, and many high GOR wells are being shut-in. The off-take is being closely regulated to prevent any further decline in the reservoir pressure. For this purpose, GC-I area along with another GC area has been studied to identify pressure compartments. Current pressure level has been estimated for each of these compartments. The compartments named as regions are shown in Figure 6. Also shown is the gas-oil-contact on the map and the faults. To determine the desirable off-take rate for each region, a plot of rate and pressure has been made with time on x-axis (Figure 7). The rate at which the pressure appears to have been stabilized over a period was identified. Based on the PVT data and producing GOR, the corresponding subsurface rate has been calculated. This becomes the target subsurface rate for the region. The current subsurface rate is computed for the region. Wells are examined in detail for their performance behavior, and their recommended rates are matched to achieve the target subsurface rate for the compartment. Based on the study, three Wara completions were shut-in, and oil rates were revised in other completions to a rate of 7500 bopd from eight completions. This has saved nearly 10 MMscfd of gas from being bled off. The shut-in bottom-hole pressure measurements are planned to assess the pressure behavior.
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