Arunesh Kumar

Engineered LCM Design Yields Novel Activating Material for Potential Application in Severe Lost Circulation Scenarios

Particulate lost circulation materials (LCM) that work for severe-to-total losses are difficult, if not impossible, to find. Solutions that are effective for lower loss rates do not perform well at higher loss rates. Many LCM formulations have been used to treat severe losses, but their design and use has been more trial and error based mostly upon successful case histories. This paper describes the development of a combination of materials that is used in conjunction with other Engineered, Composite Solutions (ECS) to further enhance their performance. A novel combination of swelling materials, retarder, and fibers with a large aspect ratio is proposed as an activator that can be deployed with ECS typically available on the rig. The activator was designed and tested under conditions that qualitatively resemble severe lost circulation scenarios (large fractures). A shale swell meter was modified to qualitatively compare the swelling behaviour of different materials under different temperatures and retarder concentrations. A polyacrylamide-based swelling material was found to be sensitive to both temperature and retarder concentration. A newly sourced, potentially reservoir-friendly swelling material was found to be sensitive to temperature only. The activator-ECS combinations were tested for plugging capability with Permeability Plugging Apparatus (PPA) test equipment using different size tapered slots. Data from these modified PPA tests were used to determine the best combination of activator and ECS for plugging a particular-sized fracture simulated by the tapered slot. Field applications of systems that led to this proposed approach are discussed along with laboratory data comparing the swelling behaviour of different materials as related to mixing and pumping times. Introduction Lost circulation (Messenger 1981), the complete loss of drilling fluid in to the formation, is a perennial issue that translates to billions of dollars annually in NPT and cost of replacing the solutions. Solutions to arrest lost circulation, Lost Circulation Materials (LCM), are also well known and available. For many years, cost and local availability have been the primary driving forces behind the selection of LCMs. Solutions for drilling fluid losses sometimes also depend on formation type. In sandstone type formations, lost circulation through natural or artificial flow paths up to 2500 microns can be arrested with particulate LCMs. Numerous solution types and case histories can be easily found by a simple search on Onepetro. But dealing with lost circulation and providing solutions in formations with severe-total losses, requires planning, rigorous testing on existing solutions, and sometimes new solutions altogether. Due to various natural fractures or vugs, carbonate formations are another type which may require novel LCMs. Most of the time, particulate LCMs do not work in carbonate formations and some sort of chemical sealant solution is explored. On the other hand, increased demand for hydrocarbons has inspired the industry to explore hydrocarbon targets once considered unreachable. This has led to drilling deeper and in harsher environments. Lost circulation in such difficult environments just adds to the operator’s costs. In cases where both situations are present, like when drilling in highly fractured formations or in carbonate formations that are in deep, harsh environments, costs associated with lost circulation (NPT) increase dramatically. Hence it is prudent to invest time and resources in finding new LCMs, solutions, and LCM evaluation techniques that would help quantify LCM performance. Whitfill 2010, Kumar 2010, 2011, Savari 2011, 2012, and Kulkarni 2012, 2012 have demonstrated the advantages of looking into LCMs using new tools, new methods for testing, and new combinations of LCMs.

Leveraging Emerging Technologies to Increase Production from Unconventional Reservoirs: Case Study of India

With a sustained growth rate of 6.2%, India is set to become the third largest economy following the USA and Chinaby 2035. In accordance with the growth rate, it is estimated that Indias import dependence is likely to increase from the current level of 72% to approximately 90% by 2035. With a large dependency on imports to meet commercial energy requirements, the demand/supply gap in oil and gas in Indiawill inevitably grow.Unconventional energy resources are becoming increasingly more important in the quest for energy security because of the continuing decline of production from proven reserves (4 to 6% decline has been observed in mature fields), accompanied by the increasing price of crude oil and natural gas. Potential sources of unconventional energyin India, proven or speculated, are coalbed methane (CBM), shale oil/gas, tight gas, and gas hydrates. With the recent advancement in 3D seismic analysis and technologies developed to analyze core samples, these have enabled a better understanding of CBM fields and other unconventional reservoirs. Because of the low permeability of these formations, economical production from unconventional reserves can only be obtained using a hydraulic-fracturing stimulation technique. Advancements in fracturing techniques from the conventional “perf-and-plug” method to multistage fracturing have enabled stimulation treatments in long intervals in a rapid and cost-effective manner. The use of advanced and proven numerical simulators in designing hydraulic-fracturing treatments has exponentially increased the success of treatments. Development of cleaner and environmentally acceptable fluids for stimulation treatments has reduced formation damage and is critical for effective stimulation of these unconventional sources of energy. Case studies from Indian fields where such emerging and effective technologies are being implemented are presented. Best practices developed to exploit CBM reservoirs and lessons learned from the mature fields in overcoming several operational challenges are discussed. Introduction India, an emerging economy, has undergone unprecedented levels of economic expansion, along with countries like China, Russia, Mexico, and Brazil. With a gross domestic product (GDP) growth rate of 8.8% in Q1 2010, by 2035 India is set to become the third largest economy following the USA and China, assuming the forecasted compounded annual growth rate (CAGR) of 6.2%. The GDP of India grew from USD 36 billion to 1.25 trillion over the last five decades. This expansion increased primary energy consumption in India by about 5% (CAGR) over the last two decades; whereas, for the rest of the world, this increase was only 2% (CAGR). Indiacomprises 16% of the total world population and,with a CAGR of 1.54%, it is expected to cross 1.5 billion by 2035; therefore, energy will be one of the most critical aspects supporting the economy and human development. According to British Petroleum statistics (BP Statistical Review of World Energy), India has only 0.4% of the world’s proven oil reserves and 0.6% of the world’s natural gas reserves. With the current rate of oil production, these proven reserves will meet the needs of the Indian economy for 20 or more years.The demand/supply mismatch for oil and gas is inevitable, and Indias dependence on imported hydrocarbons is likely to increase from its current level. To cope with increasingly active manufacturing and production sectors, and the rising per capita energy consumption, Indiamust strategically rebuild and shift its energy consumption portfolio. Tackling the energy crisis through judicious use of abundantly available renewable energy resources, such as biomass, solar, and wind energy, and unconventional oil and gas sources, must be given the highest priority. In 2009, only 5.9% of the total energy requirement was met through