Improving the Performance of Drilling Fluid Using MgO Nano Particles

One of the most important factors that cause formation damage is drilling fluid invasion caused by mud filtration. Hence, it is essential to minimize the mud filtration in order to reduce its damage to the formation using drilling fluid additives that control and minimize the filtration rate. Magnesium Oxide (MgO) nanoparticles at different masses (0.01, 0.05, 0.07, 0.1, and 0.2) gm with water base mud have been investigated in this research to measure its effect on the filtration rate. Four types of drilling fluid are used in this research; API water base mud WBM, Saturated salt water mud, DURA THERM mud and polymer mud. Filtration rate was tested under high temperature high pressure (HTHP) conditions; at (75 and 100) C and (500 psi), and at room temperature and pressure at (100 psi). The viscosity of all drilling fluid types is measured using a rotational viscometer at room temperature and atmospheric pressure. In general, the results showed that adding MgO nano particle helped in reducing the filtration rate of drilling fluid, the best results were gained in DURA THERM mud and Saturated Salt Water Mud at MgO concentrationof 0.07gm and 0.2gm, respectively; where the filtrate reduction 60% at 100 C. Also, MgO addition improves rheological properties and drilling fluid stability


Introduction
Mud and filtration loss within the formation during drilling and completion operations, have direct effect on bore hole stability, the formation damage.Filtrate loss occurs in the high permeability formation where the drilling fluid filters through the wellbore and invades the formation. As a result of the mud filtration, the solid residue of the drilling fluid will form a layer of mud deposition which called cake on borehole wall.
In high permeability formation, high pressure difference between the wellbore and the formation, and thick mud cake caused by high filtration rate can cause the drill pipe sticking.
Drilling operation considered as HTHP if bore hole static temperature and the pressure exceeds (350 o F, 25.000 psi). However, as the depth of the drilling wells keeps increasing, more severe drilling conditions can be expected, which may exceed 600 o F temperature and 40,000 psi pressure [1]. Most organic filtration control additives degradation begins when temperatures exceed 100C, so it is very important to find other alternatives that can be used in HTHP conditions. Formation damage is related more to the type of filtrate than to theamount of filtrate lost to a formation. If the filtrate reacts with the formation solids or formation fluids, that cause a reduction in permeability [2].
The nanoparticle additives are explored as an alternative to the polymer based additives.
Inorganic characteristics of the nanoparticles additives are expected to stabilize the drilling fluids even at high temperature and high pressure conditions. [1] Used three types of nanoparticales (Nickle, copper and Cobalt) to replace polymer additives in drilling fluids.
They found that these additives lose their effectiveness at high temperatures and when

No.20 Journal of Petroleum Research & Studies
(JPR&S) small amount of these materials had been used, the mud exhibited not only excellent shearthinning behavior but also stable rheological properties at high temperature.Jimet al.used two types of mud (water base mud and salt mud) with two types of nano additives (Graphene oxide and carbon nano tube), they gained a good result on rheological properties but the fluid loss control still an issue with these fluids [3]. Abdul Razak et al.used Multi Walled Carbon Nano Tubes (MWCNT) to improve the rheological properties of two mud types (water base mud and ester base mud), they showed good results on rheological and filtration properties with increasing MWCVT particle mass in ester base mud, they also concluded that increasing temperature affected on rheological, filteration and stability properties of both mud types [4]. SiO 2 ) in water base mud, they found that the reduction of filtration efficiency increased with increasing Fe 2 O 3 concentration while silica nano powder was unstable under different temperatures [7].
The objective of this research is to investigate the influence of MgO nano particle at different concentrations on filtrate volume at HTHP conditions. Four types of drilling fluid have been used WBM, Dura THERM mud, saturated salt water mud and polymer mud.

Materials
MgO NP was equipped from Sky Spring Nano materials; it has size 20 nm with 99% purity. Bentonite clay and other mud materials were supplied from Iraqi drilling company. The copolymers (TS30LC AND TS705) were equipped from SNF FLOERGER.

Experiments
This study will focus on specific conditions, where at the large depths temperature degree and pressureincreases, certainly when drilling fluid passage through these   Bentonite used as a base for the preparation of the drilling fluid. In this study, a specific amount of bentonite, related to each type mud, was added into 350 ml of tap water. The drilling fluid was hydrated overnight, after nearly 16 hstirred by Hamilton beach mixer    Filter Losses, ml  Figures (8 and 9). Filter cake, mm

3-2 Rheological Properties
The effect of MgO NP on Rheological properties of four drilling fluid types is shown in Figures (10 and 11)