Design and evaluation of wellbore strengthening materials for fractured reservoirs

Gargılı, Uğur
The lost circulation is a primary consideration while drilling through fractured carbonate formations. Uncontrolled lost circulation may result in high nonproductive drilling time and cost, stuck pipe, side-tracks, blowouts and occasionally, the abandonment of expensive wells depending upon the severity of the loss. Additionally, drill solids entering the reservoir as a result of lost circulation may plug the pore throats, leading to a significant decrease in production. In the industry, there are two approaches to struggle with loss circulation; to treat (control and stop) losses after they occur, or alternatively strengthen the loss zones to prevent losses. Indeed, it has been proved that it is easier and more effective to prevent occurrence of losses than to attempt to control and stop them once they started. Preventive method is also known as wellbore strengthening. The method aims to both alter stresses around wellbore and minimize fluid loss. They are effective not only on natural fractures but also induced fractures which occurs during drilling. The objective of this study is to determine optimum concentration and particle size distribution for fractured reservoir zones. A polymer-based reservoir drill-in fluid supported by wellbore strengthening materials (WSM) was used in this study. Sized ground marble (GM) was chosen as a WSM because of its hydrochloric acid solubility and reservoir non-damaging nature. Sized GM was used as a WSM in different concentration and in different particle size range. The experiments were conducted by using Permeability Plugging Apparatus (PPA). Fractured formations were simulated by using metal slotted disks with fracture width of 400, 800 and 1200 microns. Tests were conducted at room temperature (about 20 to 25 degrees Celcius). During the study, a total 269 tests are run to investigate the effect of different particle size distribution, concentration and fracture width. The results have been compared according to maximum sealing time required to reach assumed pressure and fluid loss values, therefore, optimum composition has been determined.


Design And Evaluation Of Wellbore Strengthening Materials For Fractured Reservoirs
Gargılı, Uğur; Gücüyener, İ. Hakkı; Durgut, İsmail; Doğan, H. Ali; Ay, Ahmet (2022-1-01)
Fractured formations are commonly encountered while drilling carbonate reservoirs. Drilling of fractured formations usually results in lost circulation. In some cases, target zones cannot be reached due severe to lost circulation incidents. Fractures encountered before reaching target zones can be sealed off by using wellbore strengthening materials (WSM). WSM are drilling fluid additives which are specially sized and designed particulates. They are generally used to strengthen the wellbore and to prevent t...
Numerical modeling of counter-current spontaneous imbibition during underbalanced drilling
Naseri, Masoud; Sınayuç, Çağlar (2012-09-10)
Mud solid and filtrate invasion are the most common causes of formation damage during overbalanced drilling (OBD), which is a method of drilling in which the wellbore pressure remains greater than formation pressure. During the past ten years, underbalanced drilling operations (UBD), which can be defined as a drilling method in which the wellbore pressure is less than formation pressure, has been growing due to their applications such as prevention of lost circulation, reduction of filtration lost in natura...
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Artun, Emre; Khoei, Ali Aghazadeh; Köse, Kutay (Springer Science and Business Media LLC, 2016-7-19)
Cyclic pressure pulsing with nitrogen is studied for hydraulically fractured wells in depleted reservoirs. A compositional simulation model is constructed to represent the hydraulic fractures through local-grid refinement. The process is analyzed from both operational and reservoir/hydraulic-fracture perspectives. Key sensitivity parameters for the operational component are chosen as the injection rate, lengths of injection and soaking periods and the economic rate limit to shut-in the well. For the reservo...
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High drilling fluid circulation rate is often needed for effective transportation of cuttings in horizontal and extended reach wells, which may not be always achievable due to the risk of fracturing the rock by increased bottom hole dynamic pressure and also limit of pumps capacity. Keeping the bottom hole pressure low enough while increasing the flow rate is, therefore, a major challenge in horizontal well drilling operations. A potential solution to this problem would be to use drag reducing additives in ...
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The studies conducted on hole cleaning have been started with single phase drilling fluids for vertical holes in 1930’s, and have reached to multiphase drilling fluids for directional and horizontal wells today. The influence of flow rate and hole inclination on cuttings transport has been well understood, and many studies have been conducted on effective hole cleaning either experimentally or theoretically. However, neither the hydraulic behavior nor the hole cleaning mechanism of gasified drilling fluids ...
Citation Formats
U. Gargılı, “Design and evaluation of wellbore strengthening materials for fractured reservoirs,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Petroleum and Natural Gas Engineering., Middle East Technical University, 2019.