Mhemed, Mohamad (Mabruk Oil Operation) | Elrotob, Nagib (Mabruk Oil Operation) | Elsadawi, Abubakr (Mabruk Oil Operation) | Ben Abdalla, Mohamed (Schlumberger Oilfield Services) | Sherik, Ayoub (Schlumberger Oilfield Services)
For two wells, performing continuous N2 lifting in an offshore environment for weeks to produce a large quantity of aquifer water that had crossed into oil-bearing zones during a long shut-in period would involve high operational and logistical risks and require a large capital investment, which was not proven economical. As an alternative, a Rigless coiled tubing (CT) gas lift system, which uses gas cap energy, was chosen as an efficient, reliable, and cost-effective technique to revive oil production from the two offshore wells.
The technique involved running CT inside the production tubing. The CT was then hung up on an additional tubing hanger installed on the production tree. The injection rate and injection pressure were supplied by a choke manifold connected to a gas well that had high wellhead pressure. The gas was injected down continuously through CT, which lifted the standing water in the production tubing annulus to surface. Production logging tools, simulation models, and flow performance applications were used to
Estimate the volume of water crossed into oil-bearing zones Identify the time needed to revive the wells
Estimate the volume of water crossed into oil-bearing zones
Identify the time needed to revive the wells
The CT gas lift system was found to be the most efficient and cost-effective way to revive production from dead wells. In this application, the free available energy of the only gas well in the field, which was drilled in the gas cap, was used to supply the required gas rate and injection pressure.
The following steps were completed with the collaboration of all parties:
Successful installation of CT in production tree via additional retrievable tubing hanger Gas pressure and gas rate supplied and controlled by a choke manifold Real-time support to guide the operation towards success Successful retrieval of CT when the operation was over
Successful installation of CT in production tree via additional retrievable tubing hanger
Gas pressure and gas rate supplied and controlled by a choke manifold
Real-time support to guide the operation towards success
Successful retrieval of CT when the operation was over
As expected, each well took nearly 45 days of continuous lifting to reach the pre-estimated water cut for the wells to be self-lifting. CT was then successfully retrieved, and the wells continued flowing naturally with considerable rates. The oil rate gain for both wells was around 4,000 BOPD.
This methodology has been approved and adopted by the operator for future similar cases as a cost-effective method to revive oil production from dead wells.
The novelty of the technique comes from the utilization of gas cap energy in the form of high wellhead pressure of the only gas well in the field, which was drilled in the gas cap, as a source of injection pressure and injection rate. This innovative technique made reviving dead wells possible without changing wellhead configuration or investing in weeks of costly N2 kickoff operations.
Schnitzler, Eduardo (Petrobras) | Ferreira Gonçalez, Luciano (Petrobras) | Savoldi Roman, Roger (Petrobras) | Atanásio Santos da Silva Filho, Djalma (Petrobras) | Marques, Marcello (Petrobras) | Corona Esquassante, Ricardo (Petrobras) | Denadai, Nilson José (Petrobras) | Feliciano da Silva, Manoel (Petrobras) | Rosas Gutterres, Fábio (Petrobras) | Signorini Gozzi, Danilo (Petrobras)
Pre-salt heterogeneous carbonate reservoirs typically present long net pays, high production/injection rates and some flow assurance risks. This paper presents general information, results and lessons learned regarding the installation of Intelligent Well Completion (IWC) in Santos Basin Pre-Salt Cluster (SBPSC) wells. It also presents some important improvements to be introduced in the future IWC systems specification and qualification based on the lessons learnt in these projects, setting some new challenges to the industry.
The benefits expected with the use of IWC are achieved at the expense of challenging well engineering, since well completion design becomes more complex and well construction risks increase. Detailed and integrated planning is essential for the success of the operations, starting at the earliest phases of the well design and continued through detailed execution plans. The use of standardized practices and procedures has led to significant increases on installation performance. On the other hand, an open mind and a constant search for improvements allowed new solutions and procedures to be developed throughout the years. Regarding the system integration, a flexible and standardized control architecture was developed to allow combining different IWC providers and subsea vendors, which proved to be a successful approach.
The most important improvement in IWC installation was the anticipation of the acid stimulation, nowadays performed before the vertical Wet Christmas Tree (WCT) installation. In order to achieve this goal some crucial improvements were gradually implemented in the stimulation practices, such as, an initial injectivity increase solution and some new acid diversion solutions, which allowed eliminating the use of coiled tubing and, as a consequence, the need of a subsea test tree. The well design team conducted an integrated risk assessment to properly evaluate the new practices and establish some actions to reduce the risks. Intense communication between production zones was observed during the acid job in some of the initial wells, ruining the gains of the IWC. After a comprehensive analysis, some possible causes were identified and with the new stimulation practices this issue was eliminated.
Over the years, with the introduction of several improvements, some of them presented in this paper, the well completion duration was reduced to less than 50% of the one observed in the initial wells. This major performance increase has been essential to keep this deepwater projects feasible, especially in the oil scenario seen in recent years. Some of the new practices and lessons learned in this 100 wells equipped with IWC has set groundbreaking practices for Brazilian pre-salt fields development and may stand as a reference for the industry in similar deepwater projects. Additional requirements for future systems are expected to improve even further the performance in this scenario.
Ryan, M. (Baker Hughes, a GE Company) | Gohari, K. (Baker Hughes, a GE Company) | Bilic, J. (Baker Hughes, a GE Company) | Livescu, S. (Baker Hughes, a GE Company) | Lindsey, B. J. (Baker Hughes, a GE Company) | Johnson, A. (Murphy Oil Company) | Baird, J. (Murphy Oil Company)
Development of unconventional reservoirs in North America has increased significantly over the past decade. The increased activity in this space has provided significant data with respect to through-tubing drillouts which had previously not been attainable. This paper is focused on using the field data from the Montney and Duvernay formations along with laboratory data and numerical modeling to understand the hole cleanout associated with through-tubing drillouts of frac plugs.
Initially, an extensive full-scale flow loop laboratory testing program was conducted to obtain data on debris transportation for hole cleanout during through-tubing applications. The testing was conducted on various coiled tubing (CT)-production tubing configurations using various solid particles. The laboratory data was used to develop empirical correlations needed for a transient debris transport model. This model was then used for frac plug drillouts to ensure successful hole cleaning in actual field applications. Computational fluid dynamics (CFD) modelling was also used to further understand and quantify the differences between the laboratory data, field data and transient debris transport model results.
The objective of the work conducted was to gain a better understanding of debris transport and validate the empirical modelling approach developed for hole cleaning. The validation process was conducted in several stages. The first stage was to validate the laboratory data against the Montney and Duvernay field data. The second stage was to verify the results obtained from the empirical model against the results obtained from a computational fluid dynamic model. The results from both modelling approaches were lastly compared to the field data. All these results challenge the current industry's understanding and best practices for through-tubing drillouts in the Montney and Duvernay formations. With the contentious increase of lateral lengths and higher stage counts, the process of drilling out frac plugs has become more complex. This study explicitly benefits all operators in their ever-increasing need to understand their frac plug drillout operations to ensure efficient, cost effective, and most importantly, consistent and repeatable results.
While efficient results for frac plug drillout operations have been accomplished to date, the on-going feedback from the field has been the requirement to produce repeatable drillouts. This paper is the first to show a holistic approach for obtaining a transient debris transport model used for through-tubing drillouts of frac plugs. The novelty also consists of the transient debris transport model validation through laboratory data and actual Montney and Duvernay field data.
Penny, Scott (Petrospec Engineering Inc.) | Karanikas, John M (Salamander Solutions Inc.) | Barnett, Jonathan (Salamander Solutions Inc.) | Harley, Guy (Salamander Solutions Inc.) | Hartwell, Chase (Petrospec Engineering Inc.) | Waddell, Trent (Petrospec Engineering Inc.)
Downhole electric heating has historically been unreliable or limited to short, often vertical, well sections. Technology improvements over the past several years now allow for reliable, long length, relatively high powered, downhole electric heating suitable for extended-reach horizontal wells. The application of this downhole electric heating technology in two different horizontal cold-producing heavy oil wells in Alberta is presented.
The first field case study discusses the application of electric heating in a mature, depleted field as a secondary recovery method while the second case study examines a virgin heavy oil reservoir, where cold production by artificial lift was economically challenged. The completion, installation, expected and actual results of both cases studies are compared and contrasted.
Both field deployments demonstrate the benefits and efficacy of applying downhole electric heating. In the case of the mature depleted field, electric heating resulted in a 4X-5X increase in oil rate, sustained over a period of close to two years. The energy ratio of the heating value of the incremental produced oil to the injected heat was slightly over 7.0. In the virgin heavy oil field, electric heating reduced the viscosity of the oil in the wellbore from time zero, which allows for higher rates of oil production along the complete length of the long horizontal lateral at higher, if desired, bottomhole pressures than in a cold-producing well. This degree of freedom may ultimately allow for an operating policy that suppresses excessive production of dissolved gas, thereby helping conserve reservoir energy. Early production data in this field show 4X-6X higher oil rates form the heated well than from the cold-producing benchmark well in the same reservoir.
Numerical simulation models, which include reactions that account for the foamy nature of the produced oil and the downhole injection of heat, have been developed and calibrated against field data. The models can be used to prescribe the range of optimal reservoir and fluid properties to select the most promising targets (fields, wells) for downhole electric heating as a production optimization method, which is crucially important in the current low oil price scenario. The same models can also be used during the execution of the project to explore optimal operating conditions and operating procedures.
Downhole electric heating in long horizontal wells is now a commercially available technology that can be reliably applied as a production optimization recovery scheme in heavy oil reservoirs. Understanding the optimum reservoir conditions where the application of downhole electric heating maximizes economic benefits will assist in identifying areas of opportunity to meaningfully increase reserves and production in heavy oil reservoirs in Alberta as well as around the world.
In this paper, we tackle an old problem - production forecast - using techniques that are relatively new to the reservoir engineer toolbox. The problem at hand consists of forecasting oil production in a mature onshore field simultaneously driven by water and steam injection. However, instead of turning to traditional methods, we deploy machine-learning algorithms which will feed on a plethora of historical data to extract hidden patterns and underlying relationships with a view to forecasting oil rate. No geological model and/or numerical reservoir simulators will be needed, only 3 sets of time-series: injection history, production history and number of producers. Two Machine-Learning algorithms are used: linear-regression and recurrent neural networks.
Potapenko, Dmitriy (Schlumberger) | Theuveny, Bertrand (Schlumberger) | Williams, Ryan (Schlumberger) | Moncada, Katharine (Schlumberger) | Campos, Mario (Schlumberger) | Spesivtsev, Pavel (Schlumberger) | Willberg, Dean (Schlumberger)
Highly efficient multi-stage hydraulic fractured horizontal wellbores are the dominant completion method for many basins worldwide. One potential weakness of multi-stage hydraulic fracturing is that the later stages of the completion workflow – frac-plug drill out (FPDO) and flowback – cause large pressure fluctuations and transient flows through the perforation clusters that coincide with a period of low closure stress in the fractures. The proppant packs in the fractures during this period are fragile and prone to failure. Previously reported results show that flowback and initial production practices have a major impact on proppant production, maintenance and disposal costs and the subsequent well performance. In this paper the results from over 200 FPDO and flowback operations from the United States and Argentina are reviewed. These results show that maintaining a balanced flowrate during FPDO operations is critical for minimizing inadvertent damage to the hydraulic fracture network.
The FPDO flowrate balance is the difference between the coiled tubing injection and annular return flowrates. The magnitude and sign of the balance corresponds to the instantaneous flowrate through the open perforation clusters into or out of the hydraulic fracture network. A positive balance rate, or overbalance, injects fluid into the fracture system. A negative balance rate, or underbalance, produces stimulation or formation fluids from the fracture network. Sudden changes between these two regimes creates local flows that can be severe enough to flush large quantities of proppant out of the fractures. Our results show that high-frequency multiphase flowmeters simplify the process of maintaining balance (no inflow, no outflow). Furthermore, close monitoring of any imbalance that develops, and rapid control of the surface choke and injection rate, can provide for an efficient operation while protecting the integrity of the fracture system.
Early monitoring of flowback and production with a high frequency flowmeter was shown to be extremely useful technique for optimizing well productivity during well clean-up. This paper also shows how a dual energy gamma ray multiphase flowmeter successfully quantified proppant produced during FPDO and flowback. Examples of the dynamics of sand production are shown, as well as correlations to events of excessive underbalance conditions.
At the end of the paper we show that most of the highlighted problems can be solved through making changes to the well construction workflow and accounting for relationships between various well operations. Incorporation of this workflow enables early prediction of well performance issues and their efficient resolution.
Numerous carbonate reservoir discoveries were made in Indonesia (
The process involves multiple cycles—from formation evaluation (e.g., geomechanics analysis, design of an effective fracturing method, and production forecasting) through the economic impact to the operator. During the early phase of this integrated study, the uncertainties of all static and dynamic parameters (i.e., geological complexity, rock physics, and stress profile) were considered for fracturing design. Production performances from multiple fracturing stimulation scenarios were then modeled and compared to select the plan that optimizes production for the Berai Formation.
Results demonstrated an effective multidiscipline approach toward a comprehensive strategy to meet the ultimate objective in optimizing production. This project leveraged formation evaluation and fracturing design to deliver integrated solutions from exploration to accurate production forecast. The well stimulations were performed by carefully selecting fluid characteristics based on geological-petrophysical properties, pressure, and stress profiles within the area. Results yielded excellent production gains—for the best case, up to 50% with an average of 40% in comparison with initial production by using an acid that provides optimum fracture geometry and permeability.
This opportunity demonstrated the importance of understanding formation behavior and the parameters that aid the selection of an appropriate fracturing design for a low porosity/permeability carbonate reservoir.
This session focuses on the latest developments in drilling applications used during exploration and development of wells. These applications are design specifically to improve well costs and schedules. The overall spectrum of well planning, engineering and design, execution will be covered; along with highlights on technical solutions of key challenges in our current drilling environment. The industry, utilises tool and equipment inspection (QA & QC) as an approach to achieve drilling assurance and reliability. Several examples of initiatives to reduce Non-Productive Time (NPT) through the application of geomechanical studies and the improvement of drilling practices to minimise operational problems related to well bore stability will be covered.
Underbalanced coiled tubing drilling has continually advanced since the first trials in the 1990s but remains a relatively niche drilling technology. With UBCTD projects set to start in many countries next year, this technology may be seeing a turning point. Considering most of the rigs deal with human-machine interface systems, the role of human factors is at the heart of any successful operation. Eye-tracking technology can be useful in real-time operation centers where ocular movement data can improve the professionals’ performance. For 60% of Sub-Saharan Africa and South Asia, by cultivated land area, an acute challenge is access to water.
CCUS is an interdisciplinary research field and its broad scope means that CCUS offers numerous opportunities for science and engineering graduates, including petroleum engineers. Underbalanced coiled tubing drilling has continually advanced since the first trials in the 1990s but remains a relatively niche drilling technology. With UBCTD projects set to start in many countries next year, this technology may be seeing a turning point.