Many oilfield processes normally employed on the surface may be adapted to downhole conditions. Sometimes the design specifications for downhole processes may be looser than surface processing because control is more difficult. Partial processing, in which fluids are separated into a relatively pure phase stream and a residual mixed-phase stream, are most common. Downhole separation technology is best suited for removing the bulk (50 to 90%) of the gas or water, with downstream surface or subsea equipment being used to "polish" the streams for complete separation. In the case of gas separation, even with complete separation downhole, dissolved gas will evolve from the liquid phase as the pressure drops when the oil flows to surface.
Saikia, Partha Protim (Oil India Limited) | Dutta, Udai Anand (Oil India Limited) | Tumung, Ranjiti (Oil India Limited) | Verma, Sanjay (Oil India Limited) | Ahmed, Akhtar Uddin (Oil India Limited) | Mukerjee, Aditya (S.K.Oilfield)
Radial jet drilling is a widely used environment friendly technique to improve well productivity in tight reservoirs, accelerate production in low-to-medium permeability wells, revamp production in mature wells with formation damage. This technique has helped to enhance production from mature field by bypassing skin, extend the connectivity of the wellbore beyond the near well bore area by drilling laterals using high pressure water jet, and thereby alleviate production restrictions caused by near well bore damage and extend the reach of the wellbore far into the formation. Production, being dependent on reservoir contact of the well bore is therefore increased as average reservoir contact is enhanced by the drain holes. However, selection is equally important as all wells cannot be considered as a suitable candidate and unsuitable candidate selection can show detrimental outcomes.
The technology was applied in a sandstone reservoir where a 22 mm hole was created in the casing at the target depth and then 50 mm OD lateral of length 100m was drilled in the reservoir using high pressure hydraulic jet. The accurate placement and orientation of downhole tool plays a significant role in the success of this technology and is found to be always challenging. Preventing casing milling in undesired azimuths, eliminating chances of lateral overlapping are some challenges that essential to be addressed for gaining optimum advantages. One of the promising technologies to address these challenges was the application of Surface Recording Gyro System. The application of surface recording gyroscopic well bore navigation system provides accurate placement of tool for lateral exit in the down hole and thus enable creation of lateral in the desired direction.
This paper discusses candidate selection and execution carried out in 7 nos. of wells in OIL INDIA LIMITED utilizing surface read out gyro system, which was done for the
As stimulations and well preparation in complicated wells are capital intensive, it was critical to identify the most-suitable candidates with the available dataset before attempting well preparation and further acquisition. This was addressed through a customized workflow to design and creation of the horizontal laterals in desired azimuth utilizing the surface readout gyro system along with radial jet drilling for maximizing oil recovery.
Radzuan, Nurul Asyikin M. (PETRONAS) | Salleh, Nurfarah Izwana (PETRONAS) | Chandrakant, Ashvin Avalani (PETRONAS) | Rusman, Liyana (PETRONAS) | Zamanuri, Kautsar (PETRONAS) | Bakar, Azfar Israa Abu (PETRONAS) | Yip, Pui Mun (PETRONAS) | Jamaluddin, M. Helmi (PETRONAS) | Ghonim, Elsayed Ouda (PETRONAS) | Nambiar, Vijay (Novomet) | Alexander, Euan (Artificial Lift Solutions)
Following the first pilot success of the truly rigless 3-1/2" tubing cable deployed ESP (TTESP-CD in offshore field of Sarawak Basin, PETRONAS has taken steps to further advance in the technology development and application through more replications within Sarawak and Malay Basin. PETRONAS had been looking into a strong business case for the TTESP-CD technology for a wider application throughout Malaysia region by looking at fields with strong/moderate water drive and low bubble point pressure besides having other limitations on the platform including the facilities reliability issues. TTESP-CD are to be applied widely in Malaysia with more flexibilities in design and improvement towards the subsurface equipment, installation equipment and procedures. With the challenges in the existing completion and production requirement for replications, based on the lesson learnt from the pilot implementation, multiple improvements to the system have been done including; 1) A High Rate Slim Pump with Flexible Application 2) Alignment Tool for Cable Hanger Orientation. With this in place, more opportunities identified for the candidate selection which improve the installation philosophy specifically in dual string applications and enhance the efficiency in installation procedures. Case studies of TTESP-CD replications in Malay & Sarawak Basin for Field T, Field B and Field P presenting the best case for TTESP-CD application with improvement to design, equipment and application. These will bring additional value to PETRONAS with estimated production gain of 1.5 KBD and up to 1.2 MMSTB reserves to be monetized with additional value saving of up to RM 6 Mill. Besides the subsurface challenges, aging offshore assets brings a lot of challenges, especially on the space availability, structural integrity, power availability and distribution, instrumentation and data transmission. This requires an integrated approach from multiple disciplines in delivering the studies as per required within the targeted timeframe.
Lu, Mingjing (China University of Petroleum, Colorado School of Mines) | Su, Yuliang (China University of Petroleum) | Wang, Wendong (China University of Petroleum) | Zhang, Ge (Xianhe Oil producing Plant, Shengli Oilfield, Sinopec)
Refracturing treatment are performed since stimulation effect won't last for entire life. Screening wells for refracturing needs a systematic analysis of huge amounts of data. With literature review, it is obviously that there are many factors controlling the success of refracturing and factors may vary in different oilfields. Proper factors and data processing are the primary principle in candidate selection. The Integrated Multiple Parameters (IMP) method is presented to provide assists in selecting candidate wells.
After deeply researching over 200 restimulated wells, all factors thought to be related with success of refracturing are listed and analyzed, results show that single factor may have great influence on restimulation but no significant patterns can be obtained since too many factors making things complicated. The IMP method proposes five parameters which are all integrated by those single factors. It is emphasized that all parameters have physical or engineering meanings which makes it easier to quantify their correlation in refracturing. Besides, all the parameters are dimensionless which makes it easier for using in mathematical models and statistical analysis.
The five dimensionless parameters are developed considering the most important aspects of candidate wells selection which are showed as followed: fracture reorientation, well completion, reservoir depletion, production decline, oil-water well connectivity. Parameters are calculated for all the restimulated wells to dig into their correlation with the outcomes of refracturing. A simple decision model is built to help with screening wells for refracturing. Results shows that it is more executable to evaluate and predict the success of refracturing with these dimensionless parameters. Fracture reorientation parameter is the primary one to be considered since it leads to fracture reorientation which brings significant production increment. Then two types of potential wells are picked: (a) wells with dissatisfied initial well completion, low production decline rate and high oil-water connectivity parameter; (b) wells with satisfied initial well completion, high well completion parameter, low production decline parameter, reservoir depletion parameter and low oil-water connectivity parameter for wells that are not easy for fracture reorientation. Wells selected are proved to be refracturing potential which verify the reliability and accuracy of IMP method.
The IMP method is an improved approach integrating most of the important factors which makes candidate selection much more predictable and it succeeds in screening out more than 80% of the potential wells in field test. Also, it can be applied widely in different oilfields since all the parameters are dimensionless. By combining with some mathematical methods such as neural networks, it can even predict increment of the restimulation treatment.
Mazzlan, Khairul Akmal (PETRONAS) | Chia, Mabel Pei Chuen (PETRONAS) | Tamin, Muhammad (PETRONAS) | Tugimin, M Azri B A (PETRONAS) | Azlan, Ali Al-Amani (PETRONAS) | Michael, Lester Tugung (Schlumberger) | Sepulveda, Willem (Schlumberger) | Cortez V., Juan L. (Schlumberger) | Muhamed Salim, Muzahidin (Schlumberger) | Kalidas, Sanggeetha (Schlumberger) | Chan, Nathanael Vui Kit (Schlumberger) | Biniwale, Shripad (Schlumberger) | Serbini, Feroney (Schlumberger) | Mohd Arifin, Azahari (Schlumberger) | Tan, Tina Lee Ting (Schlumberger) | Tee, Karen Ying Chiao (Schlumberger)
‘S’ field is a mature oilfield located offshore Sabah, Malaysia. As part of the redevelopment plan, ‘S’ field was the first field selected for an end-to-end asset management Integrated Operations (IO project) where multiple workflows have been implemented for the asset operation optimization through monitoring and surveillance. One of the exclusive workflow that will be further elaborated in this paper is on Candidate Selection and Reservoir Optimization.
Although field optimization mission was ongoing, proper knowledge capture and standardization of such techniques were not adequate due to the limited data management. Lack of decision-support mechanism and most importantly the challenge was of understanding and analysing the asset performance. A key to the success of field and reservoir optimization is defining a tailored approach, for selection of right candidate and collaborative decision for well/field intervention.
With an objective of full field revitalization, the project was focused on integrated, collaborative 3R approach – Reliability, Reusability and Repeatability. Reliability component was based on capturing knowledge from experienced professionals from various domains and blending that with traditionally proven analytical techniques. Reusability was emphasized by the development of consistent and robust analysis workflows ready to use. Repeatability was aiming at standardizing the process of candidate selection and decision making to assist junior engineers.
Mukku, Vinil (Schlumberger) | Lama, Tshering (Oil India Limited) | Verma, Sanjay (Oil India Limited) | Kumar, Pankaj (Oil India Limited) | Bordeori, Krishna (Schlumberger) | Chatterjee, Chandreyi (Schlumberger) | Kumar, Arvind (Schlumberger) | Mishra, Siddharth (Schlumberger) | Sharma, Lovely (Schlumberger) | Batshas, Siddhanta (Schlumberger) | Shah, Arpit (Schlumberger) | Prasad, C. B. (Oil India Limited) | Pathak, Digantha (Oil India Limited) | Saikia, Partha Protim (Oil India Limited)
Hydraulic fracturing can establish well productivity in tight and unconventional reservoirs, accelerate production in low- to-medium permeability wells and revamp production in mature wells. However, not all wells are suitable candidates for hydraulic fracturing and the technique can be detrimental if the right candidate is not chosen. An integrated approach is required to select the wells that are the most-suitable candidates for hydraulic fracturing.
This paper discusses the hydraulic fracturing candidate selection workflow and execution carried out in the year 2015 to 2016, which has unlocked reservoir production potential of Upper Assam basin fields of Oil India Ltd. (OIL). Wells which showed poor/no inflow prior to hydraulic fracturing operations, exceeded operator expectations during post fracturing production. Better reservoir management through hydraulic fracturing, rejuvenated ceased wells with an incremental oil production rates of 1380 bopd cumulative rate from six wells, post fracturing. The candidate analysis workflow described in this paper, can serve as the best practices guide for any operator investigating workover candidates among multiple fields, with an objective of production enhancement.
A customized candidate selection methodology was developed to identify the 10 best candidates from a pool of 70 vertical/deviated wells in two phases of the hydraulic fracturing campaign. In the absence of dynamic reservoir analysis, offset well data analysis assisted in filling the data gaps by enabling geological and reservoir level understanding. Well production models were calibrated with the production history, geo-mechanical models were prepared and used in the fracture modelling to generate optimum fracture geometry and predict post-fracturing production. Wells were ranked according to incremental hydrocarbon production coupled with risk factors including completions integrity. In the execution, fracturing model was validated by performing fracturing diagnostics tests such as Step Rate and Minifrac injection. The final calibrated model was then used to design the optimum fracturing treatment. Given the age of wells and traditional completions architecture, best practices were developed to counter challenges of high pressures and rate limitations in wells with depth greater than 3500 m.
As stimulations and well preparation in completed wells are expensive, it was critical to identify the most-suitable candidates with the available dataset before attempting well preparation and further acquisition. This was addressed through a customized workflow to perform production rate transient analysis for reservoir dynamic flow properties, create synthetic geomechanical models for stress profile & fracture vertical growth estimation.
Al Kalbani, M. (Medco Oman LLC) | Al Saadi, H. (Medco Oman LLC) | Mirza, M. (Medco Oman LLC) | Kurniadi, S. D. (Schlumberger) | Hilal, Ahmed (Schlumberger) | Al Kalbani, M. S. (Schlumberger) | Kelkar, S. (Schlumberger)
When oil prices are low, the oil industry tends to reduce its capital expenditure to fund new projects, such as exploration and development projects. The reduction in exploration activity ultimately affects the operators’ reserve balance. These conditions push each operator to use innovative solutions to increase reserves. Hydraulic fracturing is considered one of these solutions because it enables revisiting the possibility of producing an uneconomic reservoir with the existing wells. One reservoir that is being reevaluated is the Karim formation located in the Karim Small Fields (KSF), the Sultanate of Oman.
The Karim formation is divided into three segments, with the most promising being the Lower Khaleel, which was initially considered uneconomic to develop. The Khaleel is a sandstone formation at approximately 2000 m depth, with fair porosity and permeability and containing moderate-viscosity oil. The current recovery factor in the Khaleel is still less than 5%, and it is not considered for a full-field development plan due to low production results.
Because the wells drilled in the Khaleel formation were not prepared for a fracturing operation, several challenges appeared during early review, including the well trajectory and azimuth, completion condition, intervention strategy, data availability, and reservoir understanding on the formation water source and its connection to the Khaleel. The project was separated into three phases: feasibility and technical study phase, fracturing trials and evaluation phase, and fracturing understanding and optimization phase. Results are available for the first two phases, and a plan has been formulated for the third phase.
The feasibility and technical study involves understanding the geology, geomechanics, and petrophysics of the wells in which a fracturing operation was performed previously in a different formation. This study was followed by a candidate selection step involving more than 10 existing wells. The candidate selection process used a novel workflow to incorporate all the challenges into the selection criteria. Results of the candidate selection phase led to selection of the top three wells for fracturing operations in the Khaleel formation. Two out of three wells were selected for hydraulic fracturing treatment in the initial trial phase. Observations and results have been obtained from the execution of the trial hydraulic fracture jobs in these wells.
The Sanga-Sanga PSC fields are located onshore Mahakam delta, East Kalimantan, Indonesia. Since the 1970s, they have produced over 80% of originally estimated gas in place with the remaining gas locked up in low permeability sands. A prize of at least 0.75 Tcf would be achievable, if these sub milli-Darcy resources could be developed. However, previous attempts at hydraulic fracturing, over three decades, have been spectacularly ineffective and rarely enjoyed any improvement or uplift at all.
During late 2006, a detailed review of the regional stress-state and prior unsuccessful frac operations was performed. This review unearthed significant evidence of a reverse stress-ordering in the deep low permeability sands, resulting in horizontal fractures being created. While this provided some logic behind the widespread failure rate, it did not in itself offer a direct solution. However, there was also sufficient evidence from previous frac history, to indicate that the solution may lie with a pore-pressure reduction. A pilot program, with meticulous candidate selection was planned to investigate this.
Further investigation determined the presence of a strong poro-elastic relationship and it was assessed that when combined with longevity of production (30 years), that the stress-state would be substantially affected. During 2008, a suite of well candidates were carefully selected with a range of reduced pore- pressures, aligned with the poro-elastic understanding, hydraulic frac treatments were performed and the wells flowed and produced for two years to confirm productivity. The subsequent production behaviour, confirmed a very positive response and the treated wells netted substantial gas/condensate sales. Production behaviour confirmed the poro-elastic relationships and a set of absolute guidelines on candidate selection and fracture execution were created. Subsequent operations that have adhered to these strict guidelines have been extremely successful. The ability of the new approach to reverse a 30- year trend of hydraulic fracturing failure will now lead to the development of the remaining resource within the fields. An extensive treatment campaign will now be possible to perform with between 50 - 100 candidates well opportunities likely to be available in the field.
A careful assessment of the regional stress-state indicated a reverse ordering of the principal stresses as being the root cause of the poor hydraulic fracturing behaviour. However, careful consideration of the rock mechanics and a coherent pilot programme demonstrated the ability, under effective depletion conditions, to place economic and successful hydraulic fracturing treatments.
This course discusses how to select a candidate that will benefit from a workover and the extra considerations involved in a treatment design. If you are considering the possibilities of re-fracturing operations, it is critical to understand all the various conditions that must be considered. This course is of interest to petroleum engineers involved (directly or indirectly) in candidate selection, design and evaluation of re-fracturing treatments. It would be beneficial for participants to have a basic understanding of hydraulic fracturing and well completion concepts. However, the course is also of interest/value for reservoir engineering and management to understand what potentially can (and cannot) be achieved with re-fracturing.
A challenging commodity price environment has forced operators to seek methods for sharply lowering recovery cost per barrel of oil equivalent (BOE) in unconventional plays. Some reduced costs have resulted from the overcapacity of global services. Other reductions have resulted from declining industry activity, which has increased the availability of personnel and led to a renewed focus on maximizing drilling and completion (D&C) process efficiency. A portion of the recovery cost reduction has resulted directly from incremental technical innovations and process improvements that were difficult to achieve when operators and service companies were concerned chiefly with D&C execution. Older processes were designed to maximize early production, whereas a number of newer technologies focus on maximizing net present value (NPV).