Hayat, Laila (Kuwait Oil Company) | Al-Qattan, Mishari (Kuwait Oil Company) | Al-Jallad, Osama (Ingrain A Halliburton Service) | Dernaika, Moustafa (Ingrain A Halliburton Service) | Koronfol, Safouh (Ingrain A Halliburton Service) | Kayali, Anas (Ingrain A Halliburton Service) | Gonzalez, David (Ingrain A Halliburton Service)
The huge original oil in place (OOIP) of heavy oil within the upper Maastrichtian carbonate succession of Tayarat Formation in Kuwait Burgan field lead to paying more attention to its economic value and the necessity of characterizing it at multi-scales for better commercial utilization. However, its high degree of heterogeneity and complexity as a consequence of depositional and diagenetic factors, the presence of fractures in high frequencies, and existence of heavy oil (10 −15° API) with very high viscosity (80,000 cP) and non-movable bitumen in high quantities make the evaluation process very challenging and difficult. This study is aiming at characterizing these carbonate succession using a robust combination between digital and conventional methods.
One hundred seventy-seven (177) feet of representative whole core intervals were imaged by Dual Energy (DE) X-ray CT imaging technique to assess heterogeneity and identify main porosity regions within each core section for representative sample selection. The selected and extracted samples were characterized geologically and petrophysically using MICP analysis, porosity-permeability measurements, micro XCT images and petrographical analysis in order to identify main sedimentary textures and reservoir rock types (RRT), and then generate texture-based poroperm trends. The generated poroperm trends were combined with the DE derived logs in order to generate high-resolution porosity and permeability logs.
The Dual Energy CT imaging provided bulk density and photoelectric factor data that were critical for the determination of porosity and lithological variation along the core lengths. The petrographical analysis revealed common and distinctive geological textures and RRT's within the main lithological groups of the Tayarat Formation. Unique and distinctive texture-based poroperm trends were generated for each lithological group. The derived porosity and permeability logs showed a very good match with the lab-derived porosity and permeability data.
The integrated digital and conventional data at multiple scales were essential in improving our understanding of Tayarat geological and petrophysical properties.
Mukherjee, Pritish (Kuwait Oil Company) | Peres, Jose (Kuwait Oil Company) | Hayat, Laila (Kuwait Oil Company) | Anders, Dr Erik (Corsyde International Gmbh & Co. KG) | Al-Rashaid, Mona (Kuwait Oil Company) | Wunsch, David (Corsyde International Gmbh & Co. KG) | Rothenwaender, Tobias (Corsyde International Gmbh & Co. KG) | Al-Kandari, Jassim (Kuwait Oil Company)
Typically, conventional cores provide indeterminate reservoir condition; suffer loss of unknown volume of hydrocarbon fluid and mechanical integrity while being retrieved. Most laboratory analysis thereafter are simulated however it's not truly turning back the lost conditions into in-situ condition. A fully captured, and pressure retained core is thought to be a solution to provide a true micro-reservoir at surface which explains the reservoir behaviour as it behaves in subsurface. This led to successfully deploying the technology to fully capture a large diameter pressured core for the first time in conventional hydrocarbon industry in Giant Burgan Field in southeast of Kuwait in a Middle Cretaceous Clastic reservoir and also to derive a number of critical parameters from the retrieved micro-reservoir. The technology involves lowering of a large diameter pressure corer (LPC) with an outer pressure vessel and inner core barrel. After the core is cut, a drop ball mechanism sets the inward movement of the inner barrel past a spring activated pressure seal thereby keeping the core in reservoir condition. While continuous pressure recording on the retrieved core, a core analyser (PCAL) system captures multiple sets of reservoir data through a predetermined slow depressurization without hampering any operations on the rig floor. Other than measuring accurate reservoir pressure, the analytical process provided for sampling of released gases, fluids and PVT samples in addition to in-situ bubble point estimation, all at the rig site. The onsite gas analysis with compositional changes during depressurization and bubble point estimation well matched with the subsequent analysis performed on the samples in laboratory. Thus, a real representative Upper Burgan reservoir sand was retrieved containing present reservoir pressure with all fluids retained. Additionally, it provided a nearly undisturbed core with high degree of original mechanical integrity. The final depressurized core is then sent for further laboratory investigations and geological studies including slabbing and plugging. This encapsulated "micro-reservoir" is less sensitive to unexpected events like delays during retrieval and analysis, avoiding damages of the core or loss of fluids. The technology stands out against systems delivering cores at partial or no pressure retention, as it retrieves cores at formation pressure with all fluids retained and core integrity unaltered.
Bahman, Hussain (Kuwait Oil Company) | Naik, Vinay (Kuwait Oil Company) | Gazi, Naz (Kuwait Oil Company) | Malik, Abdullah (Kuwait Oil Company) | Al-Sabea, Salem (Kuwait Oil Company) | Ali, Farida (Kuwait Oil Company) | Hayat, Laila (Kuwait Oil Company) | Marafie, Hussam (Eastern United Petroleum Services) | Bibi, Amro (Eastern United Petroleum Services) | Barnett, Steven (Eastern United Petroleum Services) | Eremenko, Vasiliy B. (Eastern United Petroleum Services)
A mature field similar to the Greater Burgan field in Kuwait brings many challenges. The Kuwait Oil Company (KOC) has determined that the production from the Burgan oilfield of South & East Kuwait required to be maintained as per the production plan. Often, the unavailability of suitable surface locations posed several challenges, and drilling was one of them. A new approach helped to address these issues which otherwise delayed production. The Lower Cretaceous Burgan sands are divided into five main reservoirs; two reservoirs consist of stacked, massive fluvial channels, while the remaining three mostly consist of deltaic distributary channels and bays in a tidal delta setting, grading to shallow marine. These three reservoirs are also discontinuous, both laterally and vertically.
Every year in the Greater Burgan field, a large number of wells are drilled targeting the Cretaceous reservoirs. The Greater Burgan field has been producing for more than 60 years. Due to the unavailability of suitable surface locations, highly deviated wells are drilled, and to reach them at target reservoir, the well profile sometimes passes through faults which create partial or total losses while drilling, which results in badhole condition. In some of the wells, owing to poor hole conditions, recording openhole logs are not possible. Normally in such cases where openhole logging is not possible, PNC logs are carried out. However, recording of PNC logs is only possible after 2-3 months when the effects of mud invasion and mud filtrate are reduced to a minimum. However, this delays production.
Openhole logging had to be abandoned in one of the recently drilled wells, due to poor hole conditions. Resistivity Behind Casing tool (RBC) was proposed to be run in this well as a replacement for the PNC log. The RBC provides the measurement of reservoir bed resistivity in order to determine the oil saturation for estimating reserves. The RBC uses stationary measurements where the tool’s probes apply current to the steel casing. The current that is leaked into the formation is then measured and processed to determine the formation resistivity. The tool has a depth of investigation of 7 to 34 ft depending on the bed thickness and is therefore not influenced by the effects of mud invasion.
Based on the casedhole resistivity, potential intervals were identified, perforated and were put on early production. Casedhole resistivity paved a way for replenishment of missing data on openhole electrical logging. This has enabled early production from a well with badhole issues.
Alzankawi, Omran Mohammed (Kuwait Oil Company) | Alwazzan, Roqaia Mustafa (Kuwait Oil Company) | Shuber, Hussain Hashin (Kuwait oil company) | Al-Ghareeb, Aishah Yousef (Kuwait oil company) | Kotecha, Rohit Kumar (Kuwait Oil Company) | Mudavakkat, Anandan (Kuwait oil company) | Bardalaye, Jayanta (Kuwait Oil Company) | Hayat, Laila (Kuwait oil company) | Sinha, Satyendra Prasad (Kuwait Oil Company) | Capello, Maria A (Kuwait Oil Company) | Al-Hamoud, Jamal (Kuwait Oil Company)
As part of KOC strategy to develop the technical skills of the new recruits this paper will present a series of best practices related to decision workflows during drilling of horizontal wells through a recognized multidisciplinary team which optimized the preparation level and knowledge standard for the young generation through practical workshop and in short period.
The best practices identified included aspects related to reservoir management, location selection, subsurface characterization and drilling specifics. Those were the key elements in the preparation of the technical training with the support of a multidisciplinary team that proved beneficial to the decision processes and issues faced during drilling in real time workflows. However optimization of a well needs skill, knowledge, right vision and experience, hence the results of the extensive drilling campaign and different cases of horizontal wells allowed the establishment of a practical training workshop protocol using actual acquired data for the planning, follow-up and assessment of drilling operations, which is now used in Fields Development South and East Kuwait. The practical workshop encompassed two case histories of horizontal wells where good decision procedure resulted in avoiding complications during drilling and effectively optimized most of the drilling path.
This practical, interactive workshop was successful in developing with an integrated framework, the necessary skills in the participants, in all technical disciplines involved, namely Geosciences, Petroleum Engineering and Reservoir Engineering, in a pioneer effort of the Greater Burgan teams, not used before in KOC for training.
The impact of this workshop was to enhance the experience of the young professionals in Petroleum Engineering, Geoscience interpretation and Reservoir Management, as well as to build their integrated knowledge on horizontal drilling for the benefit of KOC, across all Directorates and possibly applicable to other oil companies.
Gomez, Ernest (Schlumberger) | Al-Faresi, Fahad A. Rahman (Kuwait Oil Company) | Belobraydic, Matthew Louis (Schlumberger) | Yaser, Muhammad (Schlumberger) | Gurpinar, Omer M. (Schlumberger) | Wang, James Tak Ming (Schlumberger) | Husain, Riyasat (Kuwait Oil Company) | Clark, William (Schlumberger) | Al-Sahlan, Ghaida Abdullah (Kuwait Oil Company) | Datta, Kalyanbrata (KOC) | Mudavakkat, Anandan (KOC) | Bond, Deryck John (Kuwait Oil Company) | Crittenden, Stephen J. (KOC) | Iwere, Fabian Oritsebemigho (Schlumberger) | Hayat, Laila (KOC) | Prakash, Anand (KOC)
The Burgan Minagish reservoir in the Greater Burgan Field is one of several reservoirs producing from the Minagish formation in Kuwait and the Divided Zone. The reservoir has been produced intermittently since the 1960s under natural depletion. A powered water-flood is currently being planned. The pressure performance of the reservoir has proved hard to explain without invoking communication with other reservoirs. Such communication could be either with other reservoirs through the regional aquifer of through faults to other reservoirs in the Greater Burgan field. Recent pressures are close to the bubble point.
A coarse simulation model of the nearby fields and the regional aquifer was constructed based on data from the fields and regional geological understanding. This model could be history matched to allow all regional pressure data to be broadly matched, a result which supports the view that communication is through the regional aquifer. Using this model to predict future pressure performance suggested that injecting at rates that exceeded voidage replacement by about 50 Mbd could keep reservoir pressure above bubble point. It was recognized that the process of history matching performance was non-unique. This is a particular concern in the context of this study because the model inputs that were varied in the history matching process included aquifer data that was very poorly constrained. To address this problem multiple history matched models were created using an assisted history matching tool. Using prediction results from the range of models has increased our confidence that a modest degree of over-injection can help maintain reservoir pressure.
This paper demonstrates the utility of computer assisted history match tools in allowing an assessment of uncertainty in a case where non-uniqueness was a particular problem. It also emphasizes the importance of understanding aquifer communication when relatively closely spaced fields are being developed.