Engineered Drilling System Approach Makes the Impossible Possible: A Case Study of Horizontal Well Drilling in Achimov Formations of Urengoyskoe Field
Authors: Dobrokhleb P. , Kretsul V. , Dymov S. , Razumniy M. , Ablaev A. , Milenkiy A. , Tarasov O. 
Published: October 2015

Abstract
The Achimov formation of the Urengoy field are considered as a promising object that by 2020 will be able to provide about 10% of gas production in Russia. Because of the complex geological conditions and a high accident rate while horizontal drilling, deposit is mostly developed by S-shaped wells. In 2013 a number of new technologies and engineering solutions in the intervals penetrated into the Achimov deposits, has allowed to drill the first time successful well with the 1000 m horizontal section length. As a result of further optimization and implementation of new solutions for each interval of the well, it was able to significantly reduce construction time and increase economic efficiency of drilling.
By collaborative efforts of the field operator, drilling contractor and oilfield services company was developed and optimized a drilling system for horizontal wells in the Achimov deposits, which included complex engineering solutions, technologies and workflows. Based on the geomechanical model was optimized drilling fluids density and rheological properties for each well section, as well as designed optimal well trajectories. For drilling performance increase there were introduced new bottomhole assemblies (BHA) with rotary steerable systems combined with positive displacement motors (PDM), selected their optimal combinations with new polycrystalline diamond (PDC) bits. With the use of a drilling process simulation package were selected optimal drilling regimes. To eliminate inefficient operations and risk mitigation, selection and evaluation of drilling and completion decisions were made within a single system.
As a result, optimization of entire drilling system, allowed to increase drilling rate in the intervals of production and liner section more than two times through the increase of ROP, number of trips reduction and flat time optimization. Application of RSS in combination with PDM section, selection of its pair with PDC bit, application of oil based mud (OBM) with a lubricant, as well as the implementation of measures aimed at keeping wellbore in a stable state and effective hole cleaning practices, that helped to reduce BHA vibrations, stick and slip of BHA while drilling and increase rate of penetration (ROP) by 59-100%, and increase the service life of BHA components. Thus achieved the ability to drill each interval per one run. The average well construction time decreased by 30%, and the fastest well was delivered to the customer by more than 2 times quiker ahead of a plan. The implementation of this approach afforded to remove restrictions associated with complecations of horizontal drilling and introduce new options for their completion, allowing to increase productivity.
As an experimental industrial tests on several wells was conducted a multi-stage hydraulic fracturing, the results significantly exceeded the previously achievable performance on initial flow rate. As a result, the operator revised its approach to the development of its license area in favor of horizontal wells, which offer a great promise in terms of improving efficiency of the deposits reserves development, as well as perspective of trial and introduction of new advanced technologies and solutions of well construction in Russia.