Achievement of Maximum Mud Weights in K-Formate WBM with Micromax and Its Successful Implementations in Deep HPHT Wells

Abstract

The Jurassic reservoirs of deep wells in Kuwait have traditionally been drilled with OBM. Barite is utilized as the weighting material in the OBM resulting damages to these reservoirs, thereby reducing the productivity to a significant extent. The higher oil to water ratio (95/5) of OBM limits the possibilities of identifying the micro fractures in reservoirs due to the limited conductive medium in OBM. Potassium formate WBM, with Manganese Tetraoxide as weighting material was successfully applied in HPHT wells overcoming these limitations. K-Formate brine was utilized up to maximum density of 12.5 ppg to reduce the impacts of solids in the mud. For the first time, maximum mud weight of 17.8 ppg was achieved operationally using micromax (Mn3O4) in this WBM. Also, for the first time in Kuwait, this kind of fluid was used to drill the section with the inclinations above 60° in deep wells. As a result of using K-Formate WBM in the reservoir sections, production increased significantly when compared to the wells drilled with OBM and barite. Wells were simulated easily without the presence of barite. Water based conductive medium gave better quality of image logs. Unlike other WBM's, K-formate WBM was stored for long periods, over a year in the mud plants without any damage to the mud properties. Recycling reduced the overall fluid costs in the subsequent wells drilled with K-formate WBM. Environmental damage due to the OBM spills and cuttings were completely avoided; K-formate WBM is highly bio-degradable under atmospheric conditions and is environmentally friendly. The experience and success gained with its use on the initial wells led to the planned usage of this WBM on all deep exploratory wells. This paper explains the experiences gained and the achievements made over the years with K-formate WBM used for drilling the deep HPHT wells.

Barite–Micromax mixture, an enhanced weighting agent for the elimination of barite sag in invert emulsion drilling fluids

“…The base fluid sample has a density of 20.4 ppg and electrical stability of 1334 V. Adding Micromax additive to the base fluid sample increased the density of the drilling mud to reach up to 21.5 ppg with 30 wt% Micromax sample, Table 3. The increase in fluid density is attributed to the high density of Micromax additive (4.8 g/cm 3 ) compared to that of barite (4.2-4.4 g/cm 3 ); therefore, less solid content will be required to provide the same density (Caenn et al 2011;Al-Muhailan et al 2014;Mustapai 2011). Conversely, increasing the concentration of Micromax additive up to 30 wt% slightly decreased the electrical stability to 1140 V because of the difference in electrical conductivity and surface charge, between Micromax additive and barite.…”

“…It has a high specific gravity (4.8), and the fine particles of Micromax additive (about 1 µm) make the abrasiveness and sag tendency of Micromax additive less than that of barite (Mustapai 2011;Ma et al 2019). Micromax additive is reservoir friendly and causes less formation damage compared with other weighting agents (Al-Muhailan et al 2014).…”

Investigating the Alteration of Sandstone Pore System and Rock Features by Role of Weighting Materials

“…1 Barite, hematite, Micromax, and ilmenite are commonly used as weighting materials for the drilling fluids to maintain the required mud density and can be used individually or in a mixture. 2,3 The formatted filter cake has to be removed after the drilling operations as its main function is to minimize the filtrate invasion during the well drilling. Filter cake removal is a required job to easily produce the reservoir hydrocarbons with good productivity, easily remove filter cake with low-cost operation.…”

“…There are many functions for the drilling fluids, and among these functions, overbalancing the formation pressure, lifting the drilled cuttings from the downhole hole to the surface mud system, and formatting a thin and low-permeability filter cake for wellbore stability . Barite, hematite, Micromax, and ilmenite are commonly used as weighting materials for the drilling fluids to maintain the required mud density and can be used individually or in a mixture. , The formatted filter cake has to be removed after the drilling operations as its main function is to minimize the filtrate invasion during the well drilling. Filter cake removal is a required job to easily produce the reservoir hydrocarbons with good productivity, easily remove filter cake with low-cost operation. , …”

Application of High-Density Brines in Drilling and Completion Fluids: Current Insights and Future Perspectives

“…The compatibility of formate-based HDBs with certain drilling fluid formulations and equipment is also a big issue. Therefore, they can be utilized for limited oilfield applications. , The most common example of formate salt used in HDBs is calcium formate (Ca­(HCOO) 2 ), which is a water-soluble salt and has a density of around 1.4 g/cm 3 . Ca­(HCOO) 2 is also employed in the completion fluids to reduce fluid loss and maintain the pressure in the borehole. ,, …”