Use of Legacy and Real Time Data to Overcome Anti Collision Challenges in Highly Congested Fields, Onshore Abu Dhabi

Abstract

Abstract Decades of field development in onshore Abu Dhabi fields has resulted in significant operational challenges in planning and drilling new wells. These highly congested fields pose a high risk of well collision due to inherent range errors in the accuracy of well survey measurements obtained during the life of individual fields and reservoirs. The study discusses a methodology for improving and normalizing the accuracy of legacy wellbore survey data to aid successful planning of recent multilateral drain hole strategy and how real time data corrections can aid in accurate wellbore placement. Multilateral wells are risked by higher collision issues for having target areas in separate azimuths from single surface location (SL). Proposed wells were subjected to lower Separation Factor (SF) due to high density of wells. In the study area, survey data of existing vertical and horizontal wells in upper and lower reservoirs in the proposed well path were studies and plotted in well sections and maps in Geological model. Well anti-collision runs of proposed lateral holes with offset wells were done in drilling planning softwares. A notional model study carried out with one of the proposed triple lateral wells in ADNOC Onshore with nearest offset wells with MSA and SAG correction resulted in collision risks being reduced by 52% and hence qualifying with the minimum SF required for safe drilling. Recent reservoir development strategy in an Abu Dhabi Onshore field is to drill trilateral wells targeting multilayered reservoirs to maximize production while optimizing sweeping efficiency. Well survey quality management with In-Field Referencing (IFR), Multi Station Analysis (MSA) and SAG Correction are the primary steps to be applied to MWD survey measurements to reduce the well collision risk. The normal well anti-collision study with nearest offset wells is mandatory as per standard drilling practices and with densely populated wells in one of the giant Abu Dhabi Onshore fields, it is becoming challenging to meet the minimum separation factor (SF>2) required by the company policy. A survey correction in all legacy wells followed by real time survey correction in triple lateral wells will add a significant value concerning collision issue in the proposed triple lateral campaign. With growing number of wells in highly congested fields, Pad drilling coupled with advance survey management technique will result in high value addition for future drilling campaigns without having collision risks and hence pave the way for future infill development strategy without subsurface space constraint.