بهينه سازي عمليات‌هاي حفاري از طريق مديريت ريسك حفاري و طراحي مسير چاه

Improving drilling speed and cost reduction through risk management and well-trajectory design

تلاش در جهت مديريت ريسك­هاي حفاري مي­تواند دستاوردهاي قابل توجهي در جهتِ به حداقل رساندن هزينه­­ها و بهبود سرعت حفاري داشته باشد. هدف اين مقاله بيان نحوه صحيح اجراي مراحل مديريت ريسك حفاري در جهت بهينه­سازي عمليات است. شناسايي، ارزيابي و اولويت­­بندي مراحلي هستند كه منجر به تشكيل ريسك فرم جامع حفاري مي­شوند. در ريسك فرم جامع حفاري تمام ريسك­ها در كنار سازند محل وقوع، احتمال وقوع و شدّت تأثير آن­ها به ترتيبِ ضريب چالش مرتب شده­اند. در مرحله­ي برنامه­ريزي، تمركز اين مطالعه بر روي جلوگيري از وقوع ريسك­ها در حفاري­هاي آينده است. به عنوان يك روش جديد در جهت دور ماندن از وقوع ريسك، با كمك گرفتن از روش زمين آماري كريجينگ، يك نقشه سه بُعدي از سرعت حفاري در تمام ميدان تشكيل شد كه در آن ميزان سرعت حفاري در نقاط مختلف ميدان و در عمق­هاي مختلف زمين نشان داده مي­شود. اين نقشه با نشان دادن تفاوت سرعت در نقاط مختلف، در حالي كه به صورت ضمني نقاط پُر ريسك و كم ريسك را نشان مي­دهد، مي­تواند براي تعيين مسير بهينه چاه در حفاري­هاي آينده مورد استفاده قرار گيرد.

Summary In this paper, in order to minimize drilling costs, it is attempted to offer a way to reduce future drilling risks through analyzing past drilling. Risk management steps are implemented for the past drillings in one of the Iranian oil fields. Before risks can be managed, they must be identified, and they must be identified before they become problems adversely affecting the project. The analysis is the conversion of risk data into risk decision-making information. The most common risks are identified and evaluated in severity and probability. Evaluated risks are classified into five categories of tolerable (T), low (L), medium (M), high (H) and intolerable (IN). A risk number is assigned to each of these categories that are prioritized based on their risk number. Finally, a consolidated list of priorities of risks is created. Planning turns risk information into decisions and actions for both the present and future. As a new method for risk aversion planning, a three-dimensional (3D) map of the geology formation in order to specify the best future well path, is designed. This shows the high risk and low risk point in the formations that drilling bit will be passed from. Drilling can be carried out in a way that there are tolerable risks.Drilling speed for the formations has been defined as a rock property (same porosity or permeability) and propagated into formations based on the past drilling data with simple kriging method. This study attempts to through an analyzing past drilling from two aspects of time and cost in one of Iranian oil fields as a case study, and then, by implementing risk managements to offer a way to reduce the risk of future drilling in the oil field. Introduction Drilling sector is one of the most important and most challenging parts of both offshore and onshore oil fields development. A great part of expenses in this development is allocated to the drilling sector. Reduction or minimization of drilling costs is an important step in order to minimize development costs. Drilling costs have become extensively large in difficult reservoirs with complex drillings so that several companies usually will make groups to share the financial risk (Bourgoyne et. al., 1986). The drilling time that is wasted as the losses such as the loss of drilling equipment and fluids, and the loss of drilling process continuity, is considered as non-productive time (NPT) (Aldred et. al., 1999). Drilling risk management can reduce and even remove these risks and their effects.